Substituted nucleosides, nucleotides and analaogs thereof

ABSTRACT

Disclosed herein are compounds of the Formula (I) and pharmaceutically acceptable salts thereof: (I) where the variables in Formula (I) are described herein. Methods of synthesizing such compounds and methods of using them to treat diseases and/or conditions such as a Picornaviridae, Flaviviridae, Filoviridae, Pneumoviridae and/or Coronaviridae viral infections are also disclosed.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified, for example, in the Application Data Sheet or Request asfiled with the present application, are hereby incorporated by referenceunder 37 CFR 1.57, and Rules 4.18 and 20.6.

BACKGROUND Field

The present application relates to the fields of chemistry, biochemistryand medicine. More particularly, disclosed herein are nucleotideanalogs, pharmaceutical compositions that include one or more nucleotideanalogs and methods of synthesizing the same. Also disclosed herein aremethods of treating viral diseases and/or conditions with a nucleotideanalog, alone or in combination therapy with one or more other agents.

Description

Nucleoside analogs are a class of compounds that have been shown toexert antiviral and anticancer activity both in vitro and in vivo, andthus, have been the subject of widespread research for the treatment ofviral infections. Nucleoside analogs are usually therapeuticallyinactive compounds that are converted by host or viral enzymes to theirrespective active anti-metabolites, which, in turn, may inhibitpolymerases involved in viral or cell proliferation. The activationoccurs by a variety of mechanisms, such as the addition of one or morephosphate groups and, or in combination with, other metabolic processes.

The challenge of developing new antiviral compounds is complicated bythe large number of different viruses and the diversity of theircharacteristics. Under the Hierarchical virus classification system,viruses are grouped by their shared properties according to four maincharacteristics: (1) nucleic acid (DNA or RNA); (2) symmetry of capsid(icosahedral, helical or complex); (3) naked or enveloped; and (4)genome architecture (positive sense or negative sense, and singlestranded or double stranded). Under the Baltimore classification,viruses are grouped according to both their genome structure and methodof replication: Group 1 (double-stranded DNA virus); Group II: (singlestranded DNA virus); Group III (double-stranded RNA virus); Group IV(single stranded positive sense RNA virus); Group V (single strandednegative sense RNA virus); Group VI (single stranded positive sense RNAvirus that replicates through a DNA intermediate); and Group VII (doublestranded DNA virus that replicates through a single stranded RNAintermediate). Within the recognized groups, there are over one hundredrecognized families of viruses, some of which are also classified intoeight different orders (Bunyavirales, Caudovirales, Herpesvirales,Ligamenvirales, Mononegavirales, Nidovirales, Picornavirales andTymovirales). In general, because of the differences between theserecognized families, there is no expectation that an antiviral compoundthat is active against a virus that is classified in any particularfamily will also be active against viruses that are classified in one ormore of the other families. For example, the viruses within thePicornaviridae, Flaviviridae, Filoviridae, Pneumoviridae andCoronaviridae families have diverse characteristics that make it verychallenging to develop an antiviral that is active against viruses intwo or more of the families.

The viruses within the Picornaviridae family are non-enveloped, positivesense, single-stranded, spherical RNA viruses with an icosahedralcapsid. They are Group IV viruses under the Baltimore classification, inthe order Picornavirales. The Picornavirus genomes are approximately 7-8kilobases long and have an IRES (Internal Ribosomal Entry Site). Theseviruses are polyadenylated at the 3′ end, and has a VPg protein at the5′ end in place of a cap. Genera within the Picornaviridae familyinclude Aphthovirus, Aquamavirus, Avihepatovirus, Cardiovirus,Cosavirus, Dicipivirus, Enterovirus, Erbovirus, Hepatovirus, Kobuvirus,Megrivirus, Parechovirus, Rhinovirus, Salivirus, Sapelovirus,Senecavirus, Teschovirus and Tremovirus.

Enteroviruses are transmitted through the fecal-oral route and/or viaaerosols of respiratory droplets, and are highly communicable. The genusof Enterovirus includes several species, including: enterovirus A,enterovirus B, enterovirus C, enterovirus D, enterovirus E, enterovirusF, enterovirus G, enterovirus Henterovirus J, rhinovirus A, rhinovirus Band rhinovirus C. Within a species of the aforementioned enterovirusesare the following serotypes: polioviruses, rhinoviruses,coxsackieviruses, echoviruses and enterovirus.

Rhinoviruses are the cause of the common cold. Rhinoviruses are namedbecause of their transmission through the respiratory route andreplication in the nose. A person can be infected with numerousrhinoviruses over their lifetime because immunity develops for eachserotype. Thus, each serotype can cause a new infection.

A hepatitis A infection is the result of an infection with a Hepatitis Avirus. Hepatovirus is transmitted through the fecal-oral route.Transmission can occur via person-to-person by ingestion of contaminatedfood or water, or through direct contact with an infectious person.

Parechovirus include human parechovirus 1 (echovirus 22), humanparechovirus 2 (echovirus 23), human parechovirus 3, human parechovirus4, human parechovirus 5 and human parechovirus 6.

The viruses with the Flaviviridae family are enveloped, positive sense,single-stranded, spherical RNA viruses with an icosahedral shapedcapsid. They are Group IV viruses under the Baltimore classification,and have not been assigned to an order. These viruses are polyadenylatedat the 5′ end but lack a 3′ polyadenylate tail. Genera within theFlaviviridae family include: Flavivirus, Pestivirus and Hepacivirus.Flaviviridae viruses are predominantly arthropod-borne, and are oftentransmitted via mosquitos and ticks. Effects/symptoms of aPicornaviridae viral infection depend on the species of virus, and caninclude, but are not limited to, fever, blisters, rash, meningitis,conjunctivitis, acute hemorrhagic conjunctivitis (AHC), sore throat,nasal congestion, runny nose, sneezing, coughing, loss of appetite,muscle aches, headache, fatigue, nausea, jaundice, encephalitis,herpangina, myocarditis, pericarditis, meningitis, Bornholm disease,myalgia, nasal congestion, muscle weakness, loss of appetite, fever,vomiting, abdominal pain, abdominal discomfort, dark urine and musclepain.

Hepaciviruses include Hepatitis C (HCV). There are various nonstructuralproteins of HCV, such as NS2, NS3, NS4, NS4A, NS4B, NS5A and NS5B. NS5Bis believed to be an RNA-dependent RNA polymerase involved in thereplication of HCV RNA. Flaviviruses include several encephalitisviruses (for example, Japanese Encephalitis virus (JEV), St. Louisencephalitis virus (SLEV) and tick-borne encephalitis virus (TBEV)),dengue virus 1-4 (DENV), West Nile virus (WNV), yellow fever virus(YFV), and Zika virus (ZIKV). A West Nile infection can lead to WestNile fever or severe West Nile disease (also called West Nileencephalitis or meningitis or West Nile poliomyelitis). Symptoms of WestNile fever include fever, headache, tiredness, body aches, nausea,vomiting, a skin rash (on the trunk of the body) and swollen lymphglands. Symptoms of West Nile disease include headache, high fever, neckstiffness, stupor, disorientation, coma, tremors, convulsions, muscleweakness and paralysis. Current treatment for a West Nile virusinfection is supportive, and no vaccination is currently available forhumans.

According to the World Health Organization (WHO), global incidence ofdengue has grown dramatically in recent decades. To date, there is notreatment for a dengue virus infection. Further, recovery from aninfection of one serotype of dengue virus provides only partial andtemporary immunity against the other serotypes. Subsequent infection(s)with another serotypes increases the likelihood of developing severedengue (previously known as dengue hemorrhagic fever). A dengueinfection is suspected with a high fever (approx. 104° F.) accompaniedby one or more of the following symptoms: severe headache, pain behindthe eyes, muscle and joint pain, nausea, vomiting, swollen glands andrash.

Yellow fever is an acute viral hemorrhagic disease. As provided by theWHO, up to 50% of severely affected persons without treatment die fromyellow fever. An estimated 200,000 cases of yellow fever, causing 30,000deaths, worldwide occur each year. As with other Flaviviruses, there isno cure or specific treatment for yellow fever, and treatment withribavirin and interferons are insufficient. Symptoms of a yellow feverinfection include fever, muscle pain with prominent backache, headache,shivers, loss of appetite, nausea, vomiting, jaundice and bleeding (forexample from the mouth, nose, eyes and/or stomach). Viruses within thePestivirus genus include bovine viral diarrhea 1, bovine viral diarrhea2, and classic swine fever virus. Viral encephalitis causes inflammationof the brain and/or meninges. Symptoms include high fever, headache,sensitivity to light, stiff neck and back, vomiting, confusion,seizures, paralysis and coma. There is no specific treatment for anencephalitis infection, such as Japanese encephalitis, St. Louisencephalitis and tick borne encephalitis. According to the Centers forDisease Control, Zika is spread mostly by the bite of an infected Aedesspecies mosquito (Ae. aegypti and Ae. albopictus) and can be passed froma pregnant woman to her fetus. Infection during pregnancy can causecertain birth defects. Many people infected with Zika virus will nothave symptoms or will only have mild symptoms. The most common symptomsof Zika are fever, rash, joint pain, and conjunctivitis. Zika is usuallymild with symptoms lasting for several days to a week. People usually donot get sick enough to go to the hospital, and they very rarely die ofZika. For this reason, many people might not realize they have beeninfected. Symptoms of Zika are similar to other viruses spread throughmosquito bites, like dengue and chikungunya.

The viruses of the Filoviridae family are enveloped, negative sense,single-stranded, linear RNA viruses. They are Group V viruses under theBaltimore classification, in the order Mononegavirales. Three generawithin the Filoviridae family are Ebolavirus, Marburgvirus and“Cuevavirus” (tentative). The five recognized species of Ebolavirus areEbola virus (EBOV), Reston ebolavirus (REBOV), Sudan ebolavirus (SEBOV),Taï Forest ebolavirus (TAFV) and Bundibugyo ebolavirus (BEBOV). The tworecognized species of Marburgvirus are Marburg virus (MARV) and Ravnvirus (RAVV). Ebolavirus and Marburgvirus are highly infectious andcontagious. Both viruses are transmitted by direct contact with theblood, body fluids and/or tissues of infected persons. Ebolavirus andMarburgvirus can also be transmitted by handling sick or dead infectedwild animals. Ebola hemorrhagic fever (EHF) is caused by an Ebolavirusinfection. Marburg virus disease (MVD) is a human disease caused by aMarburgvirus, and causes Marburgvirus hemorrhagic fever (MHF).Ebolavirus and Marburgvirus cause viral hemorrhagic fever in variousprimates, including humans.

Pneumoviridae is a relatively new virus family that was created byelevating the paramyxoviral subfamily Pneumovirinae. The viruses of thePneumoviridae family are negative sense, single-stranded, RNA viruses.They are Group V viruses under the Baltimore classification, in theorder Mononegavirales. Two genera within the Pneumoviridae family areMetapneumovirus and Orthopneumovirus. The two recognized species ofMetapneumovirus are avian metapneumovirus (AMPV) and humanmetapneumovirus (HMPV). The three recognized species of Orthopneumovirusare Bovine respiratory syncytial virus (BRSV), Human respiratorysyncytial virus (HRSV, including HRSV-A2, HRSV-B1 and HRSV-S2) andMurine pneumonia virus (MPV). Viruses in the Pneumoviridae family aretypically transmitted through respiratory secretions and are oftenassociated with respiratory infections.

Coronaviridae viruses are a family of enveloped, positive-stranded,single-stranded, spherical RNA viruses. They are Group IV viruses underthe Baltimore classification, in the order Nidovirales. Coronavirusesare named for the crown-like spikes on their surface. The Coronaviridaefamily includes two sub-families, Coronavirus and Torovirus. TheCoronavirus genus has a helical nucleocapsid, and Torovirus genus has atubular nucleocapsid. Within the Coronavirus sub-family are thefollowing genera: Alphacoronavirus, Betacoronavirus, Gammacoronavirusand Deltacoronavirus. Genera within the Torovirus sub-family areBafinivirus and Torovirus.

Human coronaviruses usually cause mild to moderate upper-respiratorytract illnesses, like the common cold, that last for a short amount oftime (although some coronaviruses can be deadly). Symptoms may includerunny nose, cough, sore throat, and fever. These viruses can sometimescause lower-respiratory tract illnesses, such as pneumonia. This is morecommon in people with cardiopulmonary disease or compromised immunesystems, or the elderly.

Middle East respiratory syndrome coronavirus (MERS-CoV) is a member ofthe Betacoronavirus genus, and causes Middle East Respiratory Syndrome(MERS). MERS is an acute respiratory illness. About half of theindividuals confirmed to have been infected with MERS died. There is nocurrent treatment or vaccine for MERS.

Another member of the Betacornavirus genus is SARS coronavirus(SARS-CoV). SARS-Co-V is the virus that causes severe acute respiratorysyndrome (SARS). SARS was first reported in Asia in February 2003. SARSis an airborne virus, and can spread by the inhalation of small dropletsof water that an infected individuals releases into the air (forexample, by coughing and/or sneezing), touching a contaminated surfaceand/or by being in close proximity of an infected individual (forexample, cared for or lived with a person known to have SARS or having ahigh likelihood of direct contact with respiratory secretions and/orbody fluids of a patient known to have SARS, including kissing orembracing, sharing eating or drinking utensils, close conversation(within 3 feet), physical examination, and any other direct physicalcontact between people).

The two genera within the Togaviridae family are Alphavirus andRubivirus. Viruses within this family are enveloped, positive-sense,single-stranded, linear RNA viruses. To date, Rubivirus has one species,Rubella virus. Viruses classified in the Alphavirus genus includeVenezuelan equine encephalitis (VEE) viruses. VEE viruses are mainlytransmitted by mosquitos and cause Venezuelan equine encephalitis andencephalomyelitis. The VEE complex of viruses includes six antigenicsubtypes (I-VI) divided by antigenic variants. Additionally, VEE virusesare divided into two groups, epizootic (or epidemic) and enzootic (orendemic). Within subtype I, the Venezuelan equine encephalomyelitisvirus (VEEV), is divided into five antigenic variants (variants AB-F).Subtype II is known as Everglades virus, subtype III as Mucambo virus,and subtype IV as Pixuna virus. Equine species along with humans can beinfected with VEE viruses. Currently, there is no vaccine available forhorses or humans.

Another member of the Alphavirus genus is Chikungunya (CHIKV).Chikungunya is an arthropod-borne virus and can be transmitted to humansby mosquitoes (such as Aedes mosquitos). Currently, there are nospecific treatments for Chikungunya, and no vaccine is currentlyavailable.

Other Alphaviruses are Barmah Forest virus, Mayaro virus (MAYV),O‘nyong’nyong virus, Ross River virus (RRV), Semliki Forest virus,Sindbis virus (SINV), Una virus, Eastern equine encephalitis virus (EEE)and Western equine encephalomyelitis (WEE). These Alphaviruses aremainly arthropod-borne, and transmitted via mosquitos.

The lack of expectation that a newly developed nucleoside analog will bepanviral, e.g., active against two or more viruses that are classifiedin different virus families, is based in part on the observation thatpanviral activity has been found for relatively few of the many knownnucleoside analogs. Although panviral activity is generally consideredto be desirable, the activity of such compounds against diverse virusesalso raises the prospect that increased off-target effects might also beobserved, leading to potential toxicity concerns that tend to slowclinical development. Thus, there remains a long-felt need for panviralnucleoside analogs, and particularly those having low toxicity.

SUMMARY

Some embodiments disclosed herein relate to a compound of Formula (I),or a pharmaceutically acceptable salt thereof. In various embodiments,compounds of Formula (I) and/or pharmaceutically acceptable saltsthereof exhibit panviral activity. Such panviral activity is surprisingbecause of the diversity of viruses against which they are active. Forexample, in some embodiments a compound of Formula (I), or apharmaceutically acceptable salt thereof, exhibits activity againstviruses that are in two or more different virus families. In someembodiments, a compound of Formula (I), or a pharmaceutically acceptablesalt thereof exhibits activity against a virus in two of more of thePicornaviridae, Flaviviridae, Filoviridae, Pneumoviridae and/orCoronaviridae families.

In some embodiments, a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof, has low toxicity. In some embodiments, acompound of Formula (I), or a pharmaceutically acceptable salt thereof,has both low toxicity and is panviral, unexpectedly exhibiting activityagainst viruses that are in two or more different virus families despiteits low toxicity.

Some embodiments disclosed herein relate to a method of amelioratingand/or treating a Picornaviridae viral infection that can includeadministering to a subject identified as suffering from thePicornaviridae viral infection an effective amount of one or morecompounds of Formula (I), or a pharmaceutically acceptable salt thereof,or a pharmaceutical composition that includes one or more compounds ofFormula (I), or a pharmaceutically acceptable salt thereof. Otherembodiments described herein relate to using one or more compounds ofFormula (I), or a pharmaceutically acceptable salt thereof, in themanufacture of a medicament for ameliorating and/or treating aPicornaviridae viral infection. Still other embodiments described hereinrelate to one or more compounds of Formula (I), or a pharmaceuticallyacceptable salt thereof, or a pharmaceutical composition that includesone or more compounds of Formula (I), or a pharmaceutically acceptablesalt thereof, that can be used for ameliorating and/or treating aPicornaviridae viral infection.

Some embodiments disclosed herein relate to a method of amelioratingand/or treating a Picornaviridae viral infection that can includecontacting a cell infected with the picornavirus with an effectiveamount of one or more compounds described herein (for example, acompound of Formula (I), or a pharmaceutically acceptable salt thereof),or a pharmaceutical composition that includes one or more compoundsdescribed herein, or a pharmaceutically acceptable salt thereof. Otherembodiments described herein relate to using one or more compoundsdescribed herein (for example, a compound of Formula (I), or apharmaceutically acceptable salt thereof) in the manufacture of amedicament for ameliorating and/or treating a Picornaviridae viralinfection that can include contacting a cell infected with thepicornavirus with an effective amount of said compound(s). Still otherembodiments described herein relate to one or more compounds describedherein (for example, a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof), or a pharmaceutical composition that includesone or more compounds described herein, or a pharmaceutically acceptablesalt thereof, that can be used for ameliorating and/or treating aPicornaviridae viral infection by contacting a cell infected with thepicornavirus with an effective amount of said compound(s).

Some embodiments disclosed herein relate to a method of inhibitingreplication of a Picornaviridae virus that can include contacting a cellinfected with the picornavirus with an effective amount of one or morecompounds described herein (for example, a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes one or more compounds described herein, or apharmaceutically acceptable salt thereof. Other embodiments describedherein relate to using one or more compounds described herein (forexample, a compound of Formula (I), or a pharmaceutically acceptablesalt thereof) in the manufacture of a medicament for inhibitingreplication of a Picornaviridae virus that can include contacting a cellinfected with the Picornaviridae virus with an effective amount of saidcompound(s). Still other embodiments described herein relate to one ormore compounds described herein (for example, a compound of Formula (I),or a pharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes one or more compounds described herein, or apharmaceutically acceptable salt thereof, that can be used forinhibiting replication of a Picornaviridae virus by contacting a cellinfected with the picornavirus with an effective amount of saidcompound(s). In some embodiments, the Picornaviridae virus can beselected from a rhinovirus, hepatitis A virus, a coxasackie virus and anenterovirus.

Some embodiments disclosed herein relate to a method of amelioratingand/or treating a Flaviviridae viral infection that can includeadministering to a subject identified as suffering from the Flaviviridaeviral infection an effective amount of one or more compounds of Formula(I), or a pharmaceutically acceptable salt thereof, or a pharmaceuticalcomposition that includes one or more compounds of Formula (I), or apharmaceutically acceptable salt thereof. Other embodiments disclosedherein relate to a method of ameliorating and/or treating a Flaviviridaeviral infection that can include contacting a cell infected with theFlaviviridae virus with an effective amount of one or more compoundsdescribed herein (for example, a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes one or more compounds described herein, or apharmaceutically acceptable salt thereof. Still other embodimentsdescribed herein relate to using one or more compounds of Formula (I),or a pharmaceutically acceptable salt thereof, in the manufacture of amedicament for ameliorating and/or treating a Flaviviridae viralinfection. Yet still other embodiments described herein relate to one ormore compounds of Formula (I), or a pharmaceutically acceptable saltthereof, or a pharmaceutical composition that includes one or morecompounds of Formula (I), or a pharmaceutically acceptable salt thereof,that can be used for ameliorating and/or treating a Flaviviridae viralinfection. Some embodiments disclosed herein relate to a method ofinhibiting replication of a Flaviviridae virus that can includecontacting a cell infected with the Flaviviridae with an effectiveamount of one or more compounds described herein (for example, acompound of Formula (I), or a pharmaceutically acceptable salt thereof),or a pharmaceutical composition that includes one or more compoundsdescribed herein, or a pharmaceutically acceptable salt thereof. Otherembodiments described herein relate to using one or more compoundsdescribed herein (for example, a compound of Formula (I), or apharmaceutically acceptable salt thereof) in the manufacture of amedicament for inhibiting replication of a Flaviviridae virus. Stillother embodiments described herein relate to one or more compoundsdescribed herein (for example, a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes one or more compounds described herein, or apharmaceutically acceptable salt thereof, that can be used forinhibiting replication of a Flaviviridae virus. In some embodiments, theFlaviviridae virus can be selected from Hepatitis C (HCV), dengue andZika.

Some embodiments disclosed herein relate to a method of amelioratingand/or treating a Filoviridae viral infection that can includeadministering to a subject identified as suffering from the Filoviridaeviral infection an effective amount of one or more compounds of Formula(I), or a pharmaceutically acceptable salt thereof, or a pharmaceuticalcomposition that includes one or more compounds of Formula (I), or apharmaceutically acceptable salt thereof. Other embodiments disclosedherein relate to a method of ameliorating and/or treating a Filoviridaeviral infection that can include contacting a cell infected with theFiloviridae virus with an effective amount of one or more compoundsdescribed herein (for example, a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes one or more compounds described herein, or apharmaceutically acceptable salt thereof. Still other embodimentsdescribed herein relate to using one or more compounds of Formula (I),or a pharmaceutically acceptable salt thereof, in the manufacture of amedicament for ameliorating and/or treating a Filoviridae viralinfection. Yet still other embodiments described herein relate to one ormore compounds of Formula (I), or a pharmaceutically acceptable saltthereof, or a pharmaceutical composition that includes one or morecompounds of Formula (I), or a pharmaceutically acceptable salt thereof,that can be used for ameliorating and/or treating a Filoviridae viralinfection. Some embodiments disclosed herein relate to a method ofinhibiting replication of a Filoviridae virus that can includecontacting a cell infected with the Filoviridae with an effective amountof one or more compounds described herein (for example, a compound ofFormula (I), or a pharmaceutically acceptable salt thereof), or apharmaceutical composition that includes one or more compounds describedherein, or a pharmaceutically acceptable salt thereof. Other embodimentsdescribed herein relate to using one or more compounds described herein(for example, a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof) in the manufacture of a medicament forinhibiting replication of a Filoviridae virus. Still other embodimentsdescribed herein relate to one or more compounds described herein (forexample, a compound of Formula (I), or a pharmaceutically acceptablesalt thereof), or a pharmaceutical composition that includes one or morecompounds described herein, or a pharmaceutically acceptable saltthereof, that can be used for inhibiting replication of a Filoviridaevirus. In some embodiments, the Filoviridae virus can be an Ebolavirusor a Marburgvirus.

Some embodiments disclosed herein relate to a method of amelioratingand/or treating a Pneumoviridae viral infection that can includeadministering to a subject identified as suffering from thePneumoviridae viral infection an effective amount of one or morecompounds of Formula (I), or a pharmaceutically acceptable salt thereof,or a pharmaceutical composition that includes one or more compounds ofFormula (I), or a pharmaceutically acceptable salt thereof. Otherembodiments disclosed herein relate to a method of ameliorating and/ortreating a Pneumoviridae viral infection that can include contacting acell infected with the Pneumoviridae virus with an effective amount ofone or more compounds described herein (for example, a compound ofFormula (I), or a pharmaceutically acceptable salt thereof), or apharmaceutical composition that includes one or more compounds describedherein, or a pharmaceutically acceptable salt thereof. Still otherembodiments described herein relate to using one or more compounds ofFormula (I), or a pharmaceutically acceptable salt thereof, in themanufacture of a medicament for ameliorating and/or treating aPneumoviridae viral infection. Yet still other embodiments describedherein relate to one or more compounds of Formula (I), or apharmaceutically acceptable salt thereof, or a pharmaceuticalcomposition that includes one or more compounds of Formula (I), or apharmaceutically acceptable salt thereof, that can be used forameliorating and/or treating a Pneumoviridae viral infection. Someembodiments disclosed herein relate to a method of inhibitingreplication of a Pneumoviridae virus that can include contacting a cellinfected with the Pneumoviridae with an effective amount of one or morecompounds described herein (for example, a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes one or more compounds described herein, or apharmaceutically acceptable salt thereof. Other embodiments describedherein relate to using one or more compounds described herein (forexample, a compound of Formula (I), or a pharmaceutically acceptablesalt thereof) in the manufacture of a medicament for inhibitingreplication of a Pneumoviridae virus. Still other embodiments describedherein relate to one or more compounds described herein (for example, acompound of Formula (I), or a pharmaceutically acceptable salt thereof),or a pharmaceutical composition that includes one or more compoundsdescribed herein, or a pharmaceutically acceptable salt thereof, thatcan be used for inhibiting replication of a Pneumoviridae virus. In someembodiments, the Pneumoviridae virus can be a human respiratorysyncytial virus.

Some embodiments disclosed herein relate to a method of amelioratingand/or treating a Coronaviridae viral infection that can includeadministering to a subject identified as suffering from theCoronaviridae viral infection an effective amount of one or morecompounds of Formula (I), or a pharmaceutically acceptable salt thereof,or a pharmaceutical composition that includes one or more compounds ofFormula (I), or a pharmaceutically acceptable salt thereof. Otherembodiments disclosed herein relate to a method of ameliorating and/ortreating a Coronaviridae viral infection that can include contacting acell infected with the Coronaviridae virus with an effective amount ofone or more compounds described herein (for example, a compound ofFormula (I), or a pharmaceutically acceptable salt thereof), or apharmaceutical composition that includes one or more compounds describedherein, or a pharmaceutically acceptable salt thereof. Still otherembodiments described herein relate to using one or more compounds ofFormula (I), or a pharmaceutically acceptable salt thereof, in themanufacture of a medicament for ameliorating and/or treating aCoronaviridae viral infection. Yet still other embodiments describedherein relate to one or more compounds of Formula (I), or apharmaceutically acceptable salt thereof, or a pharmaceuticalcomposition that includes one or more compounds of Formula (I), or apharmaceutically acceptable salt thereof, that can be used forameliorating and/or treating a Coronaviridae viral infection. Someembodiments disclosed herein relate to a method of inhibitingreplication of a Coronaviridae virus that can include contacting a cellinfected with the Coronaviridae with an effective amount of one or morecompounds described herein (for example, a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes one or more compounds described herein, or apharmaceutically acceptable salt thereof. Other embodiments describedherein relate to using one or more compounds described herein (forexample, a compound of Formula (I), or a pharmaceutically acceptablesalt thereof) in the manufacture of a medicament for inhibitingreplication of a Coronaviridae virus. Still other embodiments describedherein relate to one or more compounds described herein (for example, acompound of Formula (I), or a pharmaceutically acceptable salt thereof),or a pharmaceutical composition that includes one or more compoundsdescribed herein, or a pharmaceutically acceptable salt thereof, thatcan be used for inhibiting replication of a Coronaviridae virus. In someembodiments, the Coronaviridae virus can be a human α-coronavirus viralinfection or a human β-coronavirus viral infection.

These and other embodiments are described in greater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a reaction scheme for making compound 1.

FIG. 2 illustrates a reaction scheme for making compound 2.

FIG. 3 illustrates a reaction scheme for making compound 3.

FIG. 4 illustrates a reaction scheme for making compound 4.

FIG. 5 illustrates a reaction scheme for making compound 5.

FIG. 6 illustrates a reaction scheme for making compound 6.

FIG. 7 illustrates a reaction scheme for making compound 7.

FIG. 8 illustrates a reaction scheme for making compound 8.

DETAILED DESCRIPTION Definitions

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of ordinary skillin the art. All patents, applications, published applications and otherpublications referenced herein are incorporated by reference in theirentirety unless stated otherwise. In the event that there are aplurality of definitions for a term herein, those in this sectionprevail unless stated otherwise.

As used herein, any “R” group(s) such as, without limitation, R^(A),R^(1A)R^(2A), R^(3A), R^(4A), R^(5A), R^(6A), R^(7A), R^(8A), R^(9A),R^(10A), R^(11A), R^(12A), R^(13A), R^(14A), R^(15A), R^(16A), R^(17A),R^(18A), R^(19A), R^(20A), R^(21A), R^(22A), R^(23A), R^(24A), R^(25A),R^(26A), R^(27A), R^(28A), R^(29A), R^(30A), R^(31A), R^(a1) and R^(a2)represent substituents that can be attached to the indicated atom. An Rgroup may be substituted or unsubstituted. If two “R” groups aredescribed as being “taken together” the R groups and the atoms they areattached to can form a cycloalkyl, cycloalkenyl, aryl, heteroaryl orheterocycle. For example, without limitation, if R^(a) and R^(b) of anNR^(a)R^(b) group are indicated to be “taken together,” it means thatthey are covalently bonded to one another to form a ring:

In addition, if two “R” groups are described as being “taken together”with the atom(s) to which they are attached to form a ring as analternative, the R groups are not limited to the variables orsubstituents defined previously.

Whenever a group is described as being “optionally substituted” thatgroup may be unsubstituted or substituted with one or more of theindicated substituents. Likewise, when a group is described as being“unsubstituted or substituted” if substituted, the substituent(s) may beselected from one or more of the indicated substituents. If nosubstituents are indicated, it is meant that the indicated “optionallysubstituted” or “substituted” group may be substituted with one or moregroup(s) individually and independently selected from alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl,aryl(alkyl), heteroaryl(alkyl), (heterocyclyl)alkyl, hydroxy, alkoxy,acyl, cyano, halogen, thiocarbonyl, O-carbamyl, N-carbamyl,O-thiocarbamyl, N-thiocarbamyl, C-amido, N-amido, S-sulfonamido,N-sulfonamido, C-carboxy, O-carboxy, isocyanato, thiocyanato,isothiocyanato, nitro, silyl, sulfenyl, sulfinyl, sulfonyl, haloalkyl,haloalkoxy, trihalomethanesulfonyl, trihalomethanesulfonamido, an amino,a mono-substituted amino group and a di-substituted amino group.

As used herein, “C_(a) to C_(b)” in which “a” and “b” are integers referto the number of carbon atoms in an alkyl, alkenyl or alkynyl group, orthe number of carbon atoms in the ring of a cycloalkyl, cycloalkenyl,aryl, heteroaryl or heterocyclyl group. That is, the alkyl, alkenyl,alkynyl, ring of the cycloalkyl, ring of the cycloalkenyl, ring of thearyl, ring of the heteroaryl or ring of the heterocyclyl can containfrom “a” to “b”, inclusive, carbon atoms. Thus, for example, a “C₁ to C₄alkyl” group refers to all alkyl groups having from 1 to 4 carbons, thatis, CH₃—, CH₃CH₂—, CH₃CH₂CH₂—, (CH₃)₂CH—, CH₃CH₂CH₂CH₂—, CH₃CH₂CH(CH₃)—and (CH₃)₃C—. If no “a” and “b” are designated with regard to an alkyl,alkenyl, alkynyl, cycloalkyl cycloalkenyl, aryl, heteroaryl orheterocyclyl group, the broadest range described in these definitions isto be assumed.

As used herein, an asterisk (“*”) used with respect to a chemical groupindicates a point of attachment. For example, the asterisk in thechemical group “*—(CR^(15A)R^(16A))_(p)—O—C₁₋₂₄ alkyl” indicates thepoint of attachment for that chemical group to another group ormolecule.

As used herein, “alkyl” refers to a straight or branched hydrocarbonchain that comprises a fully saturated (no double or triple bonds)hydrocarbon group. The alkyl group may have 1 to 20 carbon atoms(whenever it appears herein, a numerical range such as “1 to 20” refersto each integer in the given range; e.g., “1 to 20 carbon atoms” meansthat the alkyl group may consist of 1 carbon atom, 2 carbon atoms, 3carbon atoms, etc., up to and including 20 carbon atoms, although thepresent definition also covers the occurrence of the term “alkyl” whereno numerical range is designated). The alkyl group may also be a mediumsize alkyl having 1 to 10 carbon atoms. The alkyl group could also be alower alkyl having 1 to 6 carbon atoms. The alkyl group of the compoundsmay be designated as “C₁-C₄ alkyl” or similar designations. By way ofexample only, “C₁-C₄ alkyl” indicates that there are one to four carbonatoms in the alkyl chain, i.e., the alkyl chain is selected from methyl,ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and t-butyl.Typical alkyl groups include, but are in no way limited to, methyl,ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl andhexyl. The alkyl group may be substituted or unsubstituted.

As used herein, “alkenyl” refers to an alkyl group that contains in thestraight or branched hydrocarbon chain one or more double bonds. Analkenyl group may be unsubstituted or substituted.

As used herein, “alkynyl” refers to an alkyl group that contains in thestraight or branched hydrocarbon chain one or more triple bonds. Analkynyl group may be unsubstituted or substituted.

As used herein, “cycloalkyl” refers to a completely saturated (no doubleor triple bonds) mono- or multi-cyclic hydrocarbon ring system. Whencomposed of two or more rings, the rings may be joined together in afused fashion. Cycloalkyl groups can contain 3 to 10 atoms in thering(s) or 3 to 8 atoms in the ring(s). A cycloalkyl group may beunsubstituted or substituted. Typical cycloalkyl groups include, but arein no way limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,cycloheptyl and cyclooctyl.

As used herein, “cycloalkenyl” refers to a mono- or multi-cyclichydrocarbon ring system that contains one or more double bonds in atleast one ring; although, if there is more than one, the double bondscannot form a fully delocalized pi-electron system throughout all therings (otherwise the group would be “aryl,” as defined herein). Whencomposed of two or more rings, the rings may be connected together in afused fashion. A cycloalkenyl can contain 3 to 10 atoms in the ring(s)or 3 to 8 atoms in the ring(s). A cycloalkenyl group may beunsubstituted or substituted.

As used herein, “aryl” refers to a carbocyclic (all carbon) monocyclicor multicyclic aromatic ring system (including fused ring systems wheretwo carbocyclic rings share a chemical bond) that has a fullydelocalized pi-electron system throughout all the rings. The number ofcarbon atoms in an aryl group can vary. For example, the aryl group canbe a C₆-C₁₄ aryl group, a C₆-C₁₀ aryl group, or a C₆ aryl group.Examples of aryl groups include, but are not limited to, benzene,naphthalene and azulene. An aryl group may be substituted orunsubstituted.

As used herein, “heteroaryl” refers to a monocyclic, bicyclic andtricyclic aromatic ring system (a ring system with fully delocalizedpi-electron system) that contain(s) one or more heteroatoms (forexample, 1 to 5 heteroatoms), that is, an element other than carbon,including but not limited to, nitrogen, oxygen and sulfur. The number ofatoms in the ring(s) of a heteroaryl group can vary. For example, theheteroaryl group can contain 4 to 14 atoms in the ring(s), 5 to 10 atomsin the ring(s) or 5 to 6 atoms in the ring(s). Furthermore, the term“heteroaryl” includes fused ring systems where two rings, such as atleast one aryl ring and at least one heteroaryl ring, or at least twoheteroaryl rings, share at least one chemical bond. Examples ofheteroaryl rings include, but are not limited to, furan, furazan,thiophene, benzothiophene, phthalazine, pyrrole, oxazole, benzoxazole,1,2,3-oxadiazole, 1,2,4-oxadiazole, thiazole, 1,2,3-thiadiazole,1,2,4-thiadiazole, benzothiazole, imidazole, benzimidazole, indole,indazole, pyrazole, benzopyrazole, isoxazole, benzoisoxazole,isothiazole, triazole, benzotriazole, thiadiazole, tetrazole, pyridine,pyridazine, pyrimidine, pyrazine, purine, pteridine, quinoline,isoquinoline, quinazoline, quinoxaline, cinnoline and triazine. Aheteroaryl group may be substituted or unsubstituted.

As used herein, “heterocyclyl” or “heteroalicyclyl” refers to three-,four-, five-, six-, seven-, eight-, nine-, ten-, up to 18-memberedmonocyclic, bicyclic and tricyclic ring system wherein carbon atomstogether with from 1 to 5 heteroatoms constitute said ring system. Aheterocycle may optionally contain one or more unsaturated bondssituated in such a way, however, that a fully delocalized pi-electronsystem does not occur throughout all the rings. The heteroatom(s) is anelement other than carbon including, but not limited to, oxygen, sulfurand nitrogen. A heterocycle may further contain one or more carbonyl orthiocarbonyl functionalities, so as to make the definition includeoxo-systems and thio-systems such as lactams, lactones, cyclic imides,cyclic thioimides and cyclic carbamates. When composed of two or morerings, the rings may be joined together in a fused fashion.Additionally, any nitrogens in a heteroalicyclic may be quaternized.Heterocyclyl or heteroalicyclic groups may be unsubstituted orsubstituted. Examples of such “heterocyclyl” or “heteroalicyclyl” groupsinclude but are not limited to, 1,3-dioxin, 1,3-dioxane, 1,4-dioxane,1,2-dioxolane, 1,3-dioxolane, 1,4-dioxolane, 1,3-oxathiane,1,4-oxathiin, 1,3-oxathiolane, 1,3-dithiole, 1,3-dithiolane,1,4-oxathiane, tetrahydro-1,4-thiazine, 2H-1,2-oxazine, maleimide,succinimide, barbituric acid, thiobarbituric acid, dioxopiperazine,hydantoin, dihydrouracil, trioxane, hexahydro-1,3,5-triazine,imidazoline, imidazolidine, isoxazoline, isoxazolidine, oxazoline,oxazolidine, oxazolidinone, thiazoline, thiazolidine, morpholine,oxirane, piperidine N-Oxide, piperidine, piperazine, pyrrolidine,pyrrolidone, pyrrolidione, 4-piperidone, pyrazoline, pyrazolidine,2-oxopyrrolidine, tetrahydropyran, 4H-pyran, tetrahydrothiopyran,thiamorpholine, thiamorpholine sulfoxide, thiamorpholine sulfone andtheir benzo-fused analogs (e.g., benzimidazolidinone,tetrahydroquinoline and 3,4-methylenedioxyphenyl).

As used herein, “aralkyl” and “aryl(alkyl)” refer to an aryl groupconnected, as a substituent, via a lower alkylene group. The loweralkylene and aryl group of an aryl(alkyl) may be substituted orunsubstituted. Examples include but are not limited to benzyl,2-phenyl(alkyl), 3-phenyl(alkyl) and naphthyl(alkyl).

As used herein, “heteroaralkyl” and “heteroaryl(alkyl)” refer to aheteroaryl group connected, as a substituent, via a lower alkylenegroup. The lower alkylene and heteroaryl group of heteroaralkyl may besubstituted or unsubstituted. Examples include but are not limited to2-thienyl(alkyl), 3-thienyl(alkyl), furyl(alkyl), thienyl(alkyl),pyrrolyl(alkyl), pyridyl(alkyl), isoxazolyl(alkyl), imidazolyl(alkyl)and their benzo-fused analogs.

A “heteroalicyclyl(alkyl)” and “heterocyclyl(alkyl)” refer to aheterocyclic or a heteroalicyclylic group connected, as a substituent,via a lower alkylene group. The lower alkylene and heterocyclyl of aheteroalicyclyl(alkyl) may be substituted or unsubstituted. Examplesinclude but are not limited tetrahydro-2H-pyran-4-yl(methyl),piperidin-4-yl(ethyl), piperidin-4-yl(propyl),tetrahydro-2H-thiopyran-4-yl(methyl) and 1,3-thiazinan-4-yl(methyl).

“Lower alkylene groups” are straight-chained —CH₂— tethering groups,forming bonds to connect molecular fragments via their terminal carbonatoms. Examples include but are not limited to methylene (—CH₂—),ethylene (—CH₂CH₂—), propylene (—CH₂CH₂CH₂—) and butylene(—CH₂CH₂CH₂CH₂—). A lower alkylene group can be substituted by replacingone or more hydrogen or deuterium of the lower alkylene group with asubstituent(s) listed under the definition of “substituted.”

As used herein, “alkoxy” refers to the formula —OR wherein R is analkyl, an alkenyl, an alkynyl, a cycloalkyl, a cycloalkenyl, aryl,heteroaryl, heterocyclyl, aryl(alkyl), (heteroaryl)alkyl or(heterocyclyl)alkyl is defined herein. A non-limiting list of alkoxys ismethoxy, ethoxy, n-propoxy, 1-methylethoxy (isopropoxy), n-butoxy,iso-butoxy, sec-butoxy, tert-butoxy, phenoxy and benzoxy. An alkoxy maybe substituted or unsubstituted.

As used herein, “acyl” refers to a hydrogen, deuterium, alkyl, alkenyl,alkynyl, or aryl connected, as substituents, via a carbonyl group.Examples include formyl, acetyl, propanoyl, benzoyl and acryl. An acylmay be substituted or unsubstituted.

As used herein, “hydroxyalkyl” refers to an alkyl group in which one ormore of the hydrogen or deuterium atoms are replaced by a hydroxy group.Exemplary hydroxyalkyl groups include but are not limited to,2-hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl and 2,2-dihydroxyethyl.A hydroxyalkyl may be substituted or unsubstituted.

As used herein, “haloalkyl” refers to an alkyl group in which one ormore of the hydrogen or deuterium atoms are replaced by a halogen (e.g.,mono-haloalkyl, di-haloalkyl and tri-haloalkyl). Such groups include butare not limited to, chloromethyl, fluoromethyl, difluoromethyl,trifluoromethyl, 1-chloro-2-fluoromethyl and 2-fluoroisobutyl. Ahaloalkyl may be substituted or unsubstituted.

As used herein, “haloalkoxy” refers to an —O-alkyl group in which one ormore of the hydrogen or deuterium atoms are replaced by a halogen (e.g.,mono-haloalkoxy, di-haloalkoxy and tri-haloalkoxy). Such groups includebut are not limited to, chloromethoxy, fluoromethoxy, difluoromethoxy,trifluoromethoxy, 1-chloro-2-fluoromethoxy and 2-fluoroisobutoxy. Ahaloalkoxy may be substituted or unsubstituted.

A “sulfenyl” group refers to an “—SR” group in which R can be hydrogen,deuterium, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl,heteroaryl, heterocyclyl, aryl(alkyl), (heteroaryl)alkyl or(heterocyclyl)alkyl. A sulfenyl may be substituted or unsubstituted.

A “sulfinyl” group refers to an “—S(═O)—R” group in which R can be thesame as defined with respect to sulfenyl. A sulfinyl may be substitutedor unsubstituted.

A “sulfonyl” group refers to an “SO₂R” group in which R can be the sameas defined with respect to sulfenyl. A sulfonyl may be substituted orunsubstituted.

An “O-carboxy” group refers to a “RC(═O)O—” group in which R can behydrogen, deuterium, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl,aryl, heteroaryl, heterocyclyl, aryl(alkyl), (heteroaryl)alkyl or(heterocyclyl)alkyl, as defined herein. An O-carboxy may be substitutedor unsubstituted.

The terms “ester” and “C-carboxy” refer to a “—C(═O)OR” group in which Rcan be the same as defined with respect to O-carboxy. An ester andC-carboxy may be substituted or unsubstituted.

A “thiocarbonyl” group refers to a “—C(═S)R” group in which R can be thesame as defined with respect to O-carboxy. A thiocarbonyl may besubstituted or unsubstituted.

A “trihalomethanesulfonyl” group refers to an “X₃CSO₂—” group whereineach X is a halogen.

A “trihalomethanesulfonamido” group refers to an “X₃CS(O)₂N(R_(A))—”group wherein each X is a halogen, and R_(A) is hydrogen, deuterium,alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl,heterocyclyl, aryl(alkyl), (heteroaryl)alkyl or (heterocyclyl)alkyl.

The term “amino” as used herein refers to a —NH₂ group.

As used herein, the term “hydroxy” refers to a —OH group.

A “cyano” group refers to a “—CN” group.

The term “azido” as used herein refers to a —N₃ group.

An “isocyanato” group refers to a “—NCO” group.

A “thiocyanato” group refers to a “—CNS” group.

An “isothiocyanato” group refers to an “—NCS” group.

A “mercapto” group refers to an “—SH” group.

A “carbonyl” group refers to a C═O group.

An “S-sulfonamido” group refers to a “—SO₂N(R_(A)R_(B))” group in whichR_(A) and R_(B) can be independently hydrogen, deuterium, alkyl,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl,heterocyclyl, aryl(alkyl), (heteroaryl)alkyl or (heterocyclyl)alkyl. AnS-sulfonamido may be substituted or unsubstituted.

An “N-sulfonamido” group refers to a “RSO₂N(R_(A))—” group in which Rand R_(A) can be independently hydrogen, deuterium, alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl,aryl(alkyl), (heteroaryl)alkyl or (heterocyclyl)alkyl. An N-sulfonamidomay be substituted or unsubstituted.

An “O-carbamyl” group refers to a “—OC(═O)N(R_(A)R_(B))” group in whichR_(A) and R_(B) can be independently hydrogen, deuterium, alkyl,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl,heterocyclyl, aryl(alkyl), (heteroaryl)alkyl or (heterocyclyl)alkyl. AnO-carbamyl may be substituted or unsubstituted.

An “N-carbamyl” group refers to an “ROC(═O)N(R_(A))—” group in which Rand R_(A) can be independently hydrogen, deuterium, alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl,aryl(alkyl), (heteroaryl)alkyl or (heterocyclyl)alkyl. An N-carbamyl maybe substituted or unsubstituted.

An “O-thiocarbamyl” group refers to a “—OC(═S)—N(R_(A)R_(B))” group inwhich R_(A) and R_(B) can be independently hydrogen, deuterium, alkyl,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl,heterocyclyl, aryl(alkyl), (heteroaryl)alkyl or (heterocyclyl)alkyl. AnO-thiocarbamyl may be substituted or unsubstituted.

An “N-thiocarbamyl” group refers to an “ROC(═S)N(R_(A))—” group in whichR and R_(A) can be independently hydrogen, deuterium, alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl,aryl(alkyl), (heteroaryl)alkyl or (heterocyclyl)alkyl. An N-thiocarbamylmay be substituted or unsubstituted.

A “C-amido” group refers to a “—C(═O)N(R_(A)R_(B))” group in which R_(A)and R_(B) can be independently hydrogen, deuterium, alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl,aryl(alkyl), (heteroaryl)alkyl or (heterocyclyl)alkyl. A C-amido may besubstituted or unsubstituted.

An “N-amido” group refers to a “RC(═O)N(R_(A))—” group in which R andR_(A) can be independently hydrogen, deuterium, alkyl, alkenyl, alkynyl,cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aryl(alkyl),(heteroaryl)alkyl or (heterocyclyl)alkyl. An N-amido may be substitutedor unsubstituted.

The term “halogen atom” or “halogen” as used herein, means any one ofthe radio-stable atoms of column 7 of the Periodic Table of theElements, such as, fluorine, chlorine, bromine and iodine.

Where the number of substituents is not specified (e.g. haloalkyl),there may be one or more substituents present. For example, “haloalkyl”may include one or more of the same or different halogens. As anotherexample, “C₁-C₃ alkoxyphenyl” may include one or more of the same ordifferent alkoxy groups containing one, two or three atoms.

As used herein, the abbreviations for any protective groups, amino acidsand other compounds, are, unless indicated otherwise, in accord withtheir common usage, recognized abbreviations, or the IUPAC-IUBCommission on Biochemical Nomenclature (See, Biochem. 11:942-944(1972)).

The term “nucleoside” is used herein in its ordinary sense as understoodby those skilled in the art, and refers to a compound composed of anoptionally substituted pentose moiety or modified pentose moietyattached to a heterocyclic base or tautomer thereof via a N-glycosidicbond, such as attached via the 9-position of a purine-base or the1-position of a pyrimidine-base. Examples include, but are not limitedto, a ribonucleoside comprising a ribose moiety and adeoxyribonucleoside comprising a deoxyribose moiety. A modified pentosemoiety is a pentose moiety in which an oxygen atom has been replacedwith a carbon and/or a carbon has been replaced with a sulfur or anoxygen atom. A “nucleoside” is a monomer that can have a substitutedbase and/or sugar moiety. Additionally, a nucleoside can be incorporatedinto larger DNA and/or RNA polymers and oligomers. In some instances,the nucleoside can be a nucleoside analog drug.

The term “nucleotide” is used herein in its ordinary sense as understoodby those skilled in the art, and refers to a nucleoside having aphosphate ester bound to the pentose moiety, for example, at the5′-position.

As used herein, the term “heterocyclic base” refers to an optionallysubstituted nitrogen-containing heterocyclyl that can be attached to anoptionally substituted pentose moiety or modified pentose moiety. Insome embodiments, the heterocyclic base can be selected from anoptionally substituted purine-base, an optionally substitutedpyrimidine-base and an optionally substituted triazole-base (forexample, a 1,2,4-triazole). The term “purine-base” is used herein in itsordinary sense as understood by those skilled in the art, and includesits tautomers. Similarly, the term “pyrimidine-base” is used herein inits ordinary sense as understood by those skilled in the art, andincludes its tautomers. A non-limiting list of optionally substitutedpurine-bases includes purine, adenine, guanine, hypoxanthine, xanthine,alloxanthine, 7-alkylguanine (e.g. 7-methylguanine), theobromine,caffeine, uric acid and isoguanine. Examples of pyrimidine-basesinclude, but are not limited to, cytosine, thymine, uracil,5,6-dihydrouracil and 5-alkylcytosine (e.g., 5-methylcytosine). Anexample of an optionally substituted triazole-base is1,2,4-triazole-3-carboxamide. Other non-limiting examples ofheterocyclic bases include diaminopurine, 8-oxo-N⁶-alkyladenine (e.g.,8-oxo-N⁶-methyladenine), 7-deazaxanthine, 7-deazaguanine,7-deazaadenine, N⁴,N⁴-ethanocytosin, N⁶,N⁶-ethano-2,6-diaminopurine,5-halouracil (e.g., 5-fluorouracil and 5-bromouracil),pseudoisocytosine, isocytosine, isoguanine, and other heterocyclic basesdescribed in U.S. Pat. Nos. 5,432,272 and 7,125,855, which areincorporated herein by reference for the limited purpose of disclosingadditional heterocyclic bases. In some embodiments, a heterocyclic basecan be optionally substituted with an amine or an enol protectinggroup(s).

The term “—N-linked amino acid” refers to an amino acid that is attachedto the indicated moiety via a main-chain amino or mono-substituted aminogroup. When the amino acid is attached in an —N-linked amino acid, oneof the hydrogen or deuteriums that is part of the main-chain amino ormono-substituted amino group is not present and the amino acid isattached via the nitrogen. N-linked amino acids can be substituted orunsubstituted.

The term “—N-linked amino acid ester derivative” refers to an amino acidin which a main-chain carboxylic acid group has been converted to anester group. In some embodiments, the ester group has a formula selectedfrom alkyl-O—C(═O)—, cycloalkyl-O—C(═O)—, aryl-O—C(═O)— andaryl(alkyl)-O—C(═O)—. A non-limiting list of ester groups includesubstituted and unsubstituted versions of the following:methyl-O—C(═O)—, ethyl-O—C(═O)—, n-propyl-O—C(═O)—, isopropyl-O—C(═O)—,n-butyl-O—C(═O)—, isobutyl-O—C(═O)—, tert-butyl-O—C(═O)—,neopentyl-O—C(═O)—, cyclopropyl-O—C(═O)—, cyclobutyl-O—C(═O)—,cyclopentyl-O—C(═O)—, cyclohexyl-O—C(═O)—, phenyl-O—C(═O)—,benzyl-O—C(═O)— and naphthyl-O—C(═O)—. N-linked amino acid esterderivatives can be substituted or unsubstituted.

The term “—O-linked amino acid” refers to an amino acid that is attachedto the indicated moiety via the hydroxy from its main-chain carboxylicacid group. When the amino acid is attached in an —O-linked amino acid,the hydrogen or deuterium that is part of the hydroxy from itsmain-chain carboxylic acid group is not present and the amino acid isattached via the oxygen. O-linked amino acids can be substituted orunsubstituted.

As used herein, the term “amino acid” refers to any amino acid (bothstandard and non-standard amino acids), including, but not limited to,α-amino acids, β-amino acids, γ-amino acids and δ-amino acids. Examplesof suitable amino acids include, but are not limited to, alanine,asparagine, aspartate, cysteine, glutamate, glutamine, glycine, proline,serine, tyrosine, arginine, histidine, isoleucine, leucine, lysine,methionine, phenylalanine, threonine, tryptophan and valine. Additionalexamples of suitable amino acids include, but are not limited to,ornithine, hypusine, 2-aminoisobutyric acid, dehydroalanine,gamma-aminobutyric acid, citrulline, beta-alanine, alpha-ethyl-glycine,alpha-propyl-glycine and norleucine.

The terms “phosphorothioate” and “phosphothioate” refer to a compound ofthe general formula

its protonated forms (for example,

and its tautomers (such as

As used herein, the term “phosphate” is used in its ordinary sense asunderstood by those skilled in the art, and includes its protonatedforms (for example,

As used herein, the terms “monophosphate,” “diphosphate,” and“triphosphate” are used in their ordinary sense as understood by thoseskilled in the art, and include protonated forms.

The terms “protecting group” and “protecting groups” as used hereinrefer to any atom or group of atoms that is added to a molecule in orderto prevent existing groups in the molecule from undergoing unwantedchemical reactions. Examples of protecting group moieties are describedin T. W. Greene and P. G. M. Wuts, Protective Groups in OrganicSynthesis, 3. Ed. John Wiley & Sons, 1999, and in J. F. W. McOmie,Protective Groups in Organic Chemistry Plenum Press, 1973, both of whichare hereby incorporated by reference for the limited purpose ofdisclosing suitable protecting groups. The protecting group moiety maybe chosen in such a way, that they are stable to certain reactionconditions and readily removed at a convenient stage using methodologyknown from the art. A non-limiting list of protecting groups includebenzyl; substituted benzyl; alkylcarbonyls and alkoxycarbonyls (e.g.,t-butoxycarbonyl (BOC), acetyl, or isobutyryl); arylalkylcarbonyls andarylalkoxycarbonyls (e.g., benzyloxycarbonyl); substituted methyl ether(e.g. methoxymethyl ether); substituted ethyl ether; a substitutedbenzyl ether; tetrahydropyranyl ether; silyls (e.g., trimethylsilyl,triethylsilyl, triisopropylsilyl, t-butyldimethylsilyl,tri-iso-propylsilyloxymethyl, [2-(trimethylsilyl)ethoxy]methyl ort-butyldiphenylsilyl); esters (e.g. benzoate ester); carbonates (e.g.methoxymethylcarbonate); sulfonates (e.g. tosylate or mesylate); acyclicketal (e.g. dimethyl acetal); cyclic ketals (e.g., 1,3-dioxane,1,3-dioxolanes and those described herein); acyclic acetal; cyclicacetal (e.g., those described herein); acyclic hemiacetal; cyclichemiacetal; cyclic dithioketals (e.g., 1,3-dithiane or 1,3-dithiolane);orthoesters (e.g., those described herein) and triarylmethyl groups(e.g., trityl; monomethoxytrityl (MMTr); 4,4′-dimethoxytrityl (DMTr);4,4′,4″-trimethoxytrityl (TMTr); and those described herein).

The term “pharmaceutically acceptable salt” refers to a salt of acompound that does not cause significant irritation to an organism towhich it is administered and does not abrogate the biological activityand properties of the compound. In some embodiments, the salt is an acidaddition salt of the compound. Pharmaceutical salts can be obtained byreacting a compound with inorganic acids such as hydrohalic acid (e.g.,hydrochloric acid or hydrobromic acid), sulfuric acid, nitric acid andphosphoric acid. Pharmaceutical salts can also be obtained by reacting acompound with an organic acid such as aliphatic or aromatic carboxylicor sulfonic acids, for example formic, acetic, succinic, lactic, malic,tartaric, citric, ascorbic, nicotinic, methanesulfonic, ethanesulfonic,p-toluenesulfonic, salicylic or naphthalenesulfonic acid. Pharmaceuticalsalts can also be obtained by reacting a compound with a base to form asalt such as an ammonium salt, an alkali metal salt, such as a sodium ora potassium salt, an alkaline earth metal salt, such as a calcium or amagnesium salt, a salt of organic bases such as dicyclohexylamine,N-methyl-D-glucamine, tris(hydroxymethyl)methylamine, C₁-C₇ alkylamine,cyclohexylamine, triethanolamine, ethylenediamine, and salts with aminoacids such as arginine and lysine.

Terms and phrases used in this application, and variations thereof,especially in the appended claims, unless otherwise expressly stated,should be construed as open ended as opposed to limiting. As examples ofany of the foregoing, the term ‘including’ should be read to mean‘including, without limitation,’ ‘including but not limited to,’ or thelike; the term ‘comprising’ as used herein is synonymous with‘including,’ ‘containing,’ or ‘characterized by,’ and is inclusive oropen-ended and does not exclude additional, unrecited elements or methodsteps; the term ‘having’ should be interpreted as ‘having at least;’ theterm ‘includes’ should be interpreted as ‘includes but is not limitedto;’ the term ‘example’ is used to provide exemplary instances of theitem in discussion, not an exhaustive or limiting list thereof; and useof terms like ‘preferably,’ ‘preferred,’ ‘desired,’ or ‘desirable,’ andwords of similar meaning should not be understood as implying thatcertain features are critical, essential, or even important to thestructure or function, but instead as merely intended to highlightalternative or additional features that may or may not be utilized in aparticular embodiment. In addition, the term “comprising” is to beinterpreted synonymously with the phrases “having at least” or“including at least”. When used in the context of a process, the term“comprising” means that the process includes at least the recited steps,but may include additional steps. When used in the context of acompound, composition or device, the term “comprising” means that thecompound, composition or device includes at least the recited featuresor components, but may also include additional features or components.Likewise, a group of items linked with the conjunction ‘and’ should notbe read as requiring that each and every one of those items be presentin the grouping, but rather should be read as ‘and/or’ unless expresslystated otherwise. Similarly, a group of items linked with theconjunction ‘or’ should not be read as requiring mutual exclusivityamong that group, but rather should be read as ‘and/or’ unless expresslystated otherwise.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity. The indefinite article “a” or “an” does not exclude aplurality. A single processor or other unit may fulfill the functions ofseveral items recited in the claims. The mere fact that certain measuresare recited in mutually different dependent claims does not indicatethat a combination of these measures cannot be used to advantage. Anyreference signs in the claims should not be construed as limiting thescope.

It is understood that, in any compound described herein having one ormore chiral centers, if an absolute stereochemistry is not expresslyindicated, then each center may be independently of R-configuration orS-configuration or a mixture thereof. Thus, the compounds providedherein may be enantiomerically pure, enantiomerically enriched, racemicmixture, diastereomerically pure, diastereomerically enriched, or astereoisomeric mixture. In addition it is understood that, in anycompound described herein having one or more double bond(s) generatinggeometrical isomers that can be defined as E or Z, each double bond maybe independently E or Z, or a mixture thereof.

Likewise, it is understood that, in any compound described, alltautomeric forms are also intended to be included. For example alltautomers of a phosphate and a phosphorothioate groups are intended tobe included. Examples of tautomers of a phosphorothioate include thefollowing:

Furthermore, all tautomers of heterocyclic bases known in the art areintended to be included, including tautomers of natural and non-naturalpurine-bases and pyrimidine-bases.

It is to be understood that where compounds disclosed herein haveunfilled valencies, then the valencies are to be filled as needed withhydrogen (also referred to as protium, hydrogen-1 or ¹H) or isotopesthereof. A suitable isotope of hydrogen is deuterium (also referred toas hydrogen-2 or ²H).

It is understood that the compounds described herein can be labeledisotopically. Substitution with isotopes such as deuterium may affordcertain therapeutic advantages resulting from greater metabolicstability, such as, for example, increased in vivo half-life or reduceddosage requirements. Each chemical element as represented in a compoundstructure may include any isotope of said element. Thus, referenceherein to a compound encompasses all potential isotopic forms unless thecontext clearly dictates otherwise or an isotope is already explicitlyspecified.

It is understood that the compounds, methods and combinations describedherein include crystalline forms (also known as polymorphs, whichinclude the different crystal packing arrangements of the same elementalcomposition of a compound), amorphous phases, salts, solvates andhydrates. In some embodiments, the compounds described herein (includingthose described in methods and combinations) exist in solvated formswith pharmaceutically acceptable solvents such as water, ethanol, or thelike. In other embodiments, the compounds described herein (includingthose described in methods and combinations) exist in unsolvated form.Solvates contain either stoichiometric or non-stoichiometric amounts ofa solvent, and may be formed during the process of crystallization withpharmaceutically acceptable solvents such as water, ethanol, or thelike. Hydrates are formed when the solvent is water, or alcoholates areformed when the solvent is alcohol. In addition, the compounds providedherein can exist in unsolvated as well as solvated forms.

Where a range of values is provided, it is understood that the upper andlower limit, and each intervening value between the upper and lowerlimit of the range is encompassed within the embodiments.

Compounds

Some embodiments disclosed herein relate to a compound of Formula (I),or a pharmaceutically acceptable salt thereof:

In various embodiments of compounds of the Formula (I), R^(1A) can beselected from the group consisting of fluoro, cyano, azido, anunsubstituted C₂₋₄ alkenyl, an unsubstituted C₂₋₄ alkynyl, anunsubstituted C₁₋₄ alkoxy, an unsubstituted C₁₋₄ alkyl, and asubstituted C₁₋₄ alkyl. In some embodiments, the unsubstituted C₁₋₄alkoxy is methoxy. In some embodiments, the unsubstituted C₁₋₄ alkyl ismethyl. In various embodiments, when R^(1A) is a substituted C₁₋₄ alkyl,it is substituted with one or more substituents selected from fluoro andchloro. For example, in some embodiments R^(1A) can be a substitutedC₁₋₄ alkyl that is selected from the group consisting of —(CH₂)₁₋₄C₁,—(CH₂)₁₋₄F, and —CHF₂. Non-limiting examples of substituted C₁₋₄ alkylthus include chloromethyl, fluoromethyl and difluoromethyl.

In some embodiments of compounds of the Formula (I), R^(1A) can becyano. The following Formulae (Ia1) is an example of embodiments ofcompounds of the Formula (I) in which the variable R^(1A) is cyano andthe variables R^(2A), R^(3A), R^(4A), R^(5A), R^(a1) and R^(a2) are asdescribed elsewhere herein.

For example, the following Formula (Ia2) is an example of an embodimentof compounds of the Formula (I):

In various embodiments of compounds of the Formula (I), R^(4A) can beselected from the group consisting of fluoro, cyano, azido, anunsubstituted C₂₋₄ alkenyl, an unsubstituted C₂₋₄ alkynyl, anunsubstituted C₁₋₄ alkoxy, an unsubstituted C₁₋₄ alkyl, and asubstituted C₁₋₄ alkyl, wherein said substituted C₁₋₄ alkyl issubstituted with one or more substituents selected from fluoro andchloro. In some embodiments, R^(4A) is selected from the groupconsisting of fluoro, cyano, azido, and an unsubstituted C₁₋₄ alkyl. Insome embodiments, R^(4A) is selected from the group consisting offluoro, cyano, azido, and C₁₋₄ alkyl substituted with one or moresubstituents selected from fluoro and chloro. In an embodiment, R^(4A)is fluoro. In another embodiment, R^(4A) is cyano. In anotherembodiment, R^(4A) is azido. In another embodiment, R^(4A) is anunsubstituted C₁₋₄ alkyl. For example, in an embodiment, R^(4A) ismethyl. In various embodiments, when R^(4A) is a substituted C₁₋₄ alkyl,it is substituted with one or more substituents selected from fluoro andchloro. For example, in some embodiments R^(4A) can be a substitutedC₁₋₄ alkyl that is selected from the group consisting of —(CH₂)₁₋₄C₁,—(CH₂)₁₋₄F and —CHF₂. Non-limiting examples of substituted C₁₋₄ alkylthus include chloromethyl, fluoromethyl and difluoromethyl. Thus, in anembodiment, the substituted C₁₋₄ alkyl is chloromethyl. In anotherembodiment, the substituted C₁₋₄ alkyl is fluoromethyl.

In various embodiments, the variables R^(2A) and R^(3A) of the formula(I) are each independently hydrogen or deuterium. In an embodiment,R^(2A) and R^(3A) are both hydrogen. In an embodiment, R^(2A) and R^(3A)are both deuterium. In an embodiment, one of R^(2A) and R^(3A) ishydrogen and the other is deuterium.

In various embodiments, the variables R^(a1) and R^(a2) of the formula(I) are each independently hydrogen or deuterium. In an embodiment,R^(a1) and R^(a2) are both hydrogen. In an embodiment, R^(a1) and R^(a2)are both deuterium. In an embodiment, one of R^(a1) and R^(a2) ishydrogen and the other is deuterium.

In some embodiments of compounds of the Formula (I), R^(1A) is selectedfrom the group consisting of fluoro, cyano, azido, an unsubstituted C₂₋₄alkenyl, an unsubstituted C₂₋₄ alkynyl, an unsubstituted C₁₋₄ alkoxy, anunsubstituted C₁₋₄ alkyl, and a substituted C₁₋₄ alkyl, and R^(4A) isselected from the group consisting of fluoro, cyano, azido, anunsubstituted C₂₋₄ alkenyl, an unsubstituted C₂₋₄ alkynyl, anunsubstituted C₁₋₄ alkoxy, an unsubstituted C₁₋₄ alkyl, and asubstituted C₁₋₄ alkyl, wherein said substituted C₁₋₄ alkyl issubstituted with one or more substituents selected from fluoro andchloro. For example, in some embodiments, R^(1A) is cyano, and R^(4A) isselected from the group consisting of fluoro, cyano, azido, anunsubstituted C₂₋₄ alkenyl, an unsubstituted C₂₋₄ alkynyl, chloromethyl,fluoromethyl, and difluoromethyl. In some embodiments, R^(1A) is cyano,and R^(4A) is fluoro. In some embodiments, R^(1A) is cyano, and R^(4A)is fluoromethyl. In some embodiments, R^(1A) is cyano, and R^(4A) ischloromethyl. In some embodiments, R^(1A) is cyano, and R^(4A) is azido.In some embodiments, both R^(1A) and R^(4A) are cyano.

In various embodiments, the variable R^(5A) of the Formula (I) isselected from the group consisting of hydrogen, an optionallysubstituted acyl, an optionally substituted O-linked amino acid,

R^(6A), R^(7A) and R^(8A) can be independently selected from absent,hydrogen, an optionally substituted C₁₋₂₄ alkyl, an optionallysubstituted C₃₋₂₄ alkenyl, an optionally substituted C₃₋₂₄ alkynyl, anoptionally substituted C₃₋₆ cycloalkyl, an optionally substituted C₃₋₆cycloalkenyl, an optionally substituted aryl, an optionally substitutedheteroaryl, an optionally substituted aryl(C₁₋₆ alkyl), an optionallysubstituted *—(CR^(15A)R^(16A))_(p)—O—C₁₋₂₄ alkyl, an optionallysubstituted *—(CR^(17A)R^(18A))_(q)—O—C₁₋₂₄ alkenyl,

In other embodiments, R^(6A) can be

and R^(7A) can be absent or hydrogen. In other embodiments, R^(6A) andR^(7A) can be taken together to form a moiety selected from anoptionally substituted

and an optionally substituted

wherein the oxygens connected to R^(6A) and R^(7A), the phosphorus andthe moiety form a six-membered to ten-membered ring system.

In some embodiments, R^(9A) can be independently selected from anoptionally substituted C₁₋₂₄ alkyl, an optionally substituted C₂₋₂₄alkenyl, an optionally substituted C₂₋₂₄ alkynyl, an optionallysubstituted C₃₋₆ cycloalkyl, an optionally substituted C₃₋₆cycloalkenyl, NR^(30A)R^(31A), an optionally substituted N-linked aminoacid and an optionally substituted N-linked amino acid ester derivative.The amino acid portion (of the optionally substituted N-linked aminoacid and the optionally substituted N-linked amino acid esterderivative) can have various stereochemical configurations. For example,the amino acid portion can be racemic, an L-stereoisomer, aD-stereoisomer or a mixture of L- and D-stereoisomers that is enrichedin one or the other of the stereoisomers. In an embodiment, theL-stereoisomer content of the amino acid portion is at least about 90%,at least about 95%, or at least about 99%, by weight based on themixture of L- and D-stereoisomers.

In some embodiments, R^(10A) and R^(11A) can be independently anoptionally substituted N-linked amino acid or an optionally substitutedN-linked amino acid ester derivative; R^(12A), R^(13A) and R^(14A) canbe independently absent or hydrogen; each R^(15A), each R^(16A), eachR^(17A) and each R^(18A) can be independently hydrogen, an optionallysubstituted C₁₋₂₄ alkyl or alkoxy; R^(19A), R^(20A), R^(22A) and R^(23A)can be independently selected from hydrogen, an optionally substitutedC₁₋₂₄ alkyl and an optionally substituted aryl; R^(21A) and R^(24A) canbe independently selected from hydrogen, an optionally substituted C₁₋₂₄alkyl, an optionally substituted aryl, an optionally substituted—O—C₁₋₂₄ alkyl, an optionally substituted —O-aryl, an optionallysubstituted —O-heteroaryl, an optionally substituted —O-monocyclicheterocyclyl and

R^(25A) and R^(29A) can be independently selected from hydrogen, anoptionally substituted C₁₋₂₄ alkyl and an optionally substituted aryl;R^(26A) and R^(27A) can be independently —C≡N or an optionallysubstituted substituent selected from C₂₋₈ organylcarbonyl, C₂₋₈alkoxycarbonyl and C₂₋₈ organylaminocarbonyl; R^(28A) can be selectedfrom hydrogen, an optionally substituted C₁₋₂₄-alkyl, an optionallysubstituted C₂₋₂₄ alkenyl, an optionally substituted C₂₋₂₄ alkynyl, anoptionally substituted C₃₋₆ cycloalkyl and an optionally substitutedC₃₋₆ cycloalkenyl; R^(30A) and R^(31A) can be independently selectedfrom hydrogen, an optionally substituted C₁₋₂₄-alkyl, an optionallysubstituted C₂₋₂₄ alkenyl, an optionally substituted C₂₋₂₄ alkynyl, anoptionally substituted C₃₋₆ cycloalkyl and an optionally substitutedC₃₋₆ cycloalkenyl; R″^(A) can be an optionally substituted C₁₋₂₄-alkyl;m and t can be independently 0 or 1; p and q can be independentlyselected from 1, 2 and 3; r can be 1 or 2; s can be 0, 1, 2 or 3; u canbe 1 or 2; and Z^(1A), Z^(2A), Z^(3A) and Z^(4A) can each independentlybe O or S.

In some embodiments, R^(5A) can be

In some embodiments, R^(6A) and R^(7A) can be both hydrogen. In otherembodiments, R^(6A) and R^(7A) can be both absent. In still otherembodiments, at least one R^(6A) and R^(7A) can be absent. In yet stillother embodiments, at least one R^(6A) and R^(7A) can be hydrogen. Thoseskilled in the art understand that when R^(6A) and/or R^(7A) are absent,the associated oxygen(s) will have a negative charge. For example, whenR^(6A) is absent, the oxygen associated with R^(6A) will have a negativecharge. In some embodiments, Z^(1A) can be O (oxygen). In otherembodiments, Z^(1A) can be S (sulfur). In some embodiments, R^(5A) canbe a monophosphate. In other embodiments, R^(5A) can be amonothiophosphate.

In some embodiments, when R^(5A) is

one of R^(6A) and R^(7A) can be hydrogen, and the other of R^(6A) andR^(7A) can be selected from an optionally substituted C₁₋₂₄ alkyl, anoptionally substituted C₃₋₂₄ alkenyl, an optionally substituted C₃₋₂₄alkynyl, an optionally substituted C₃₋₆ cycloalkyl, an optionallysubstituted C₃₋₆ cycloalkenyl, an optionally substituted aryl, anoptionally substituted heteroaryl and an optionally substitutedaryl(C₁₋₆ alkyl). In some embodiments, one of R^(6A) and R^(7A) can behydrogen, and the other of R^(6A) and R^(7A) can be an optionallysubstituted C₁₋₂₄ alkyl. In other embodiments, both R^(6A) and R^(7A)can be independently selected from an optionally substituted C₁₋₂₄alkyl, an optionally substituted C₃₋₂₄ alkenyl, an optionallysubstituted C₃₋₂₄ alkynyl, an optionally substituted C₃-6 cycloalkyl, anoptionally substituted C₃₋₆ cycloalkenyl, an optionally substitutedaryl, an optionally substituted heteroaryl and an optionally substitutedaryl(C₁₋₆ alkyl). In some embodiments, both R^(6A) and R^(7A) can be anoptionally substituted C₁₋₂₄ alkyl. In other embodiments, both R^(6A)and R^(7A) can be an optionally substituted C₃₋₂₄ alkenyl. In someembodiments, R^(6A) and R^(7A) can be independently an optionallysubstituted version of the following: myristoleyl, myristyl,palmitoleyl, palmityl, sapienyl, oleyl, elaidyl, vaccenyl, linoleyl,α-linolenyl, arachidonyl, eicosapentaenyl, erucyl, docosahexaenyl,caprylyl, capryl, lauryl, stearyl, arachidyl, behenyl, lignoceryl andcerotyl.

In some embodiments, at least one of R^(6A) and R^(7A) can be*—(CR^(15A)R^(16A))_(p)—O—C₁₋₂₄ alkyl. In other embodiments, R^(6A) andR^(7A) can be both *—(CR^(15A)R^(16A))_(p)—O—C₁₋₂₄ alkyl. In someembodiments, each R^(15A) and each R^(16A) can be hydrogen. In otherembodiments, at least one of R^(15A) and R^(16A) can be an optionallysubstituted C₁₋₂₄ alkyl. In other embodiments, at least one of R^(15A)and R^(16A) can be an alkoxy (for example, benzoxy). In someembodiments, p can be 1. In other embodiments, p can be 2. In stillother embodiments, p can be 3.

In some embodiments, at least one of R^(6A) and R^(7A) can be*—(CR^(17A)R^(18A))_(q)—O—C₂₋₂₄ alkenyl. In other embodiments, R^(6A)and R^(7A) can be both *—(CR^(17A)R^(18A))_(q)—O—C₂₋₂₄ alkenyl. In someembodiments, each R^(17A) and each R^(18A) can be hydrogen. In otherembodiments, at least one of R^(17A) and R^(18A) can be an optionallysubstituted C₁₋₂₄ alkyl. In some embodiments, q can be 1. In otherembodiments, q can be 2. In still other embodiments, q can be 3. When atleast one of R^(6A) and R^(7A) is *—(CR^(15A)R^(16A))_(p)—O—C₁₋₂₄ alkylor *—(CR^(17A)R^(18A))_(q)—O—C₂₋₂₄ alkenyl, the C₁₋₂₄ alkyl can beselected from caprylyl, capryl, lauryl, myristyl, palmityl, stearyl,arachidyl, behenyl, lignoceryl, and cerotyl, and the C₂₋₂₄ alkenyl canbe selected from myristoleyl, palmitoleyl, sapienyl, oleyl, elaidyl,vaccenyl, linoleyl, α-linolenyl, arachidonyl, eicosapentaenyl, erucyland docosahexaenyl.

In some embodiments, when R^(5A) is

at least one of R^(6A) and R^(7A) can be selected from

and the other of R^(6A) and R^(7A) can be selected from absent,hydrogen, an optionally substituted C₁₋₂₄ alkyl, an optionallysubstituted C₂₋₂₄ alkenyl, an optionally substituted C₂₋₂₄ alkynyl, anoptionally substituted C₃₋₆ cycloalkyl, an optionally substituted C₃₋₆cycloalkenyl, an optionally substituted aryl, an optionally substitutedheteroaryl and an optionally substituted aryl(C₁₋₆ alkyl).

In some embodiments, at least one of R^(6A) and R^(7A) can be

In some embodiments, both R^(6A) and R^(7A) can be

When one or both of R^(6A) and R^(7A) are

R^(19A) and R^(20A) can be independently selected from hydrogen, anoptionally substituted C₁₋₂₄ alkyl and an optionally substituted aryl;and R^(21A) can be selected from hydrogen, an optionally substitutedC₁₋₂₄ alkyl, an optionally substituted aryl, an optionally substituted—O—C₁₋₂₄ alkyl, an optionally substituted —O-aryl, an optionallysubstituted —O-heteroaryl, an optionally substituted —O-monocyclicheterocyclyl and

In some embodiments, R^(19A) and R^(20A) can be hydrogen. In otherembodiments, at least one of R^(19A) and R^(20A) can be an optionallysubstituted C₁₋₂₄ alkyl or an optionally substituted aryl. In someembodiments, R^(21A) can be an optionally substituted C₁₋₂₄ alkyl. Inother embodiments, R^(21A) can be an optionally substituted aryl. Instill other embodiments, R^(21A) can be an optionally substituted—O—C₁₋₂₄ alkyl or an optionally substituted —O-aryl. In someembodiments, R^(21A) can be an optionally substituted —O—C₁₋₂₄ alkyl, anoptionally substituted —O-aryl, an optionally substituted —O-heteroarylor an optionally substituted —O-monocyclic heterocyclyl.

In some embodiments, both R^(6A) and R^(7A) can be

When one or both of R^(6A) and R^(7A) are

R^(22A) and R^(23A) can be independently selected from hydrogen, anoptionally substituted C₁₋₂₄ alkyl and an optionally substituted aryl;R^(24A) can be independently selected from hydrogen, an optionallysubstituted C₁₋₂₄ alkyl, an optionally substituted aryl, an optionallysubstituted —O—C₁₋₂₄ alkyl, an optionally substituted —O-aryl, anoptionally substituted —O-heteroaryl, an optionally substituted—O-monocyclic heterocyclyl and

and Z^(4A) can be independently O (oxygen) or S (sulfur). In someembodiments, R^(22A) and R^(23A) can be hydrogen. In other embodiments,at least one of R^(22A) and R^(23A) can be an optionally substitutedC₁₋₂₄ alkyl or an optionally substituted aryl. In some embodiments,R^(24A) can be an optionally substituted C₁₋₂₄ alkyl. In otherembodiments, R^(24A) can be an optionally substituted aryl. In stillother embodiments, R^(24A) can be an optionally substituted —O—C₁₋₂₄alkyl or an optionally substituted —O-aryl. In some embodiments, Z^(4A)can be O (oxygen). In other embodiments, Z^(4A) can be or S (sulfur). Insome embodiments, s can be 0. In other embodiments, s can be 1. In stillother embodiments, s can be 2. In yet still embodiments, s can be 3. Insome embodiments, s can be 0, and R^(24A) can be

In some embodiments, u can be 1. In other embodiments, u can be 2. Insome embodiments, one or both of R^(6A) and R^(7A) can beisopropyloxycarbonyloxymethyl (POC). In some embodiments, one or both ofR^(6A) and R^(7A) can be pivaloyloxymethyl (POM). In some embodiments,R^(6A) and R^(7A) can be both a isopropyloxycarbonyloxymethyl group, andform a bis(isopropyloxycarbonyloxymethyl) (bis(POC)) prodrug. In someembodiments, R^(6A) and R^(7A) can be both a pivaloyloxymethyl group,and form a bis(pivaloyloxymethyl) (bis(POM)) prodrug.

In some embodiments, both R^(6A) and R^(7A) can be

wherein R^(26A) and R^(27A) can be independently —C≡N or an optionallysubstituted substituent selected from C₂₋₈ organylcarbonyl, C₂₋₈alkoxycarbonyl and C₂₋₈ organylaminocarbonyl; R^(28A) can be selectedfrom hydrogen, an optionally substituted C₁₋₂₄-alkyl, an optionallysubstituted C₂₋₂₄ alkenyl, an optionally substituted C₂₋₂₄ alkynyl, anoptionally substituted C₃₋₆ cycloalkyl and an optionally substitutedC₃₋₆ cycloalkenyl; and r can be 1 or 2.

In some embodiments, R^(6A) and R^(7A) can be both an optionallysubstituted aryl. In some embodiments, at least one of R^(6A) and R^(7A)can be an optionally substituted aryl. For example, both R^(6A) andR^(7A) can be an optionally substituted phenyl or an optionallysubstituted naphthyl. When substituted, the substituted aryl can besubstituted with 1, 2, 3 or more than 3 substituents. When more the twosubstituents are present, the substituents can be the same or different.In some embodiments, when at least one of R^(6A) and R^(7A) is asubstituted phenyl, the substituted phenyl can be a para-, ortho- ormeta-substituted phenyl.

In some embodiments, R^(6A) and R^(7A) can be both an optionallysubstituted aryl(C₁₋₆ alkyl). In some embodiments, at least one ofR^(6A) and R^(7A) can be an optionally substituted aryl(C₁₋₆ alkyl). Forexample, both R^(6A) and R^(7A) can be an optionally substituted benzyl.When substituted, the substituted benzyl group can be substituted with1, 2, 3 or more than 3 substituents. When more the two substituents arepresent, the substituents can be the same or different. In someembodiments, the aryl group of the aryl(C₁₋₆ alkyl) can be a para-,ortho- or meta-substituted phenyl.

In some embodiments, R^(6A) and R^(7A) can be both

In some embodiments, at least one of R^(6A) and R^(7A) can be

In some embodiments, R^(25A) can be hydrogen. In other embodiments,R^(25A) can be an optionally substituted C₁₋₂₄ alkyl. In still otherembodiments, R^(25A) can be an optionally substituted aryl. In someembodiments, R^(25A) can be a C₁₋₆ alkyl, for example, methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl (branched andstraight-chained) and hexyl (branched and straight-chained). In someembodiments, t can be 0. In other embodiments, t can be 1. In someembodiments, one or both of R^(6A) and R^(7A) can be a S-acylthioethyl(SATE).

In some embodiments, R^(6A) and R^(7A) can be both

In some embodiments, at least one of R^(6A) and R^(7A) can be

In some embodiments, R^(29A) can be hydrogen. In other embodiments,R^(29A) can be an optionally substituted C₁₋₂₄ alkyl. In someembodiments, R^(29A) can be a C₁₋₄ alkyl, such as methyl, ethyl,n-propyl, iso-propyl, n-butyl, iso-butyl and t-butyl. In still otherembodiments, R^(29A) can be an optionally substituted aryl, such as anoptionally substituted phenyl or an optionally substituted naphthyl. Insome embodiments, R^(6A) and R^(7A) can be both a dioxolenone group andform a dioxolenone prodrug.

In some embodiments, R^(5A) can be

R^(6A) can be

R^(7A) can be absent or hydrogen; R^(12A), R^(13A) and R^(14A) can beindependently absent or hydrogen; and m can be 0 or 1. In someembodiments, m can be 0, and R^(7A), R^(12A) and R^(13A) can beindependently absent or hydrogen. In other embodiments, m can be 1, andR^(7A), R^(12A), R^(13A) and R^(14A) can be independently absent orhydrogen. Those skilled in the art understand that when m is 0, R^(6A)can be diphosphate, when Z^(1A) is oxygen, or an alpha-thiodiphosphate,when Z^(1A) is sulfur. Likewise, those skilled in the art understandthat when m is 1, R^(6A) can be triphosphate, when Z^(1A) is oxygen, oran alpha-thiotriphosphate, when Z^(1A) is sulfur.

In some embodiments, R^(6A) and R^(7A) can be taken together to form anoptionally substituted

For example, R^(5A) can be an optionally substituted

When substituted, the ring can be substituted 1, 2, 3 or 3 or moretimes. When substituted with multiple substituents, the substituents canbe the same or different. In some embodiments, when R^(5A) is

the ring can be substituted with an optionally substituted aryl groupand/or an optionally substituted heteroaryl. An example of a suitableheteroaryl is pyridinyl. In some embodiments, R^(6A) and R^(7A) can betaken together to form an optionally substituted

such as

wherein R^(32A) can be an optionally substituted aryl, an optionallysubstituted heteroaryl or an optionally substituted heterocyclyl. Insome embodiments, R^(6A) and R^(7A) can form a cyclic1-aryl-1,3-propanyl ester (HepDirect) prodrug moiety.

In some embodiments, R^(6A) and R^(7A) can be taken together to form anoptionally substituted

wherein the oxygens connected to R^(6A) and R^(7A), the phosphorus andthe moiety form a six-membered to ten-membered ring system. Example ofan optionally substituted

include

In some embodiments, R^(6A) and R^(7A) can form a cyclosaligenyl(cycloSal) prodrug.

In some embodiments, R^(6A) and R^(7A) can be the same. In someembodiments, R^(6A) and R^(7A) can be different.

In some embodiments, Z^(1A) can be oxygen. In other embodiments, Z^(1A)can be sulfur.

In some embodiments, R^(5A) can be

In some embodiments, R^(8A) can be selected from absent, hydrogen, anoptionally substituted C₁₋₂₄ alkyl, an optionally substituted C₂₋₂₄alkenyl, an optionally substituted C₂₋₂₄ alkynyl, an optionallysubstituted C₃₋₆ cycloalkyl and an optionally substituted C₃₋₆cycloalkenyl; and R^(9A) can be independently selected from anoptionally substituted C₁₋₂₄ alkyl, an optionally substituted C₂₋₂₄alkenyl, an optionally substituted C₂₋₂₄ alkynyl, an optionallysubstituted C₃₋₆ cycloalkyl and an optionally substituted C₃₋₆cycloalkenyl. In an embodiment, R^(5A) is hydrogen,

In some embodiments, R^(A) can be hydrogen, and R^(9A) can be anoptionally substituted C₁₋₆ alkyl. Examples of suitable C₁₋₆ alkylsinclude methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tert-butyl, pentyl (branched and straight-chained) and hexyl (branchedand straight-chained). In other embodiments, R^(8A) can be hydrogen, andR^(9A) can be NR^(30A)R^(31A), wherein R³⁰ and R³¹ can be independentlyselected from hydrogen, an optionally substituted C₁₋₂₄ alkyl, anoptionally substituted C₂₋₂₄ alkenyl, an optionally substituted C₂₋₂₄alkynyl, an optionally substituted C₃₋₆ cycloalkyl and an optionallysubstituted C₃₋₆ cycloalkenyl.

In some embodiments, R^(A) can be absent or hydrogen; and R^(9A) can bean optionally substituted N-linked amino acid or an optionallysubstituted N-linked amino acid ester derivative. In other embodiments,R^(A) can be an optionally substituted aryl; and R^(9A) can be anoptionally substituted N-linked amino acid or an optionally substitutedN-linked amino acid ester derivative. In still other embodiments, R^(A)can be an optionally substituted heteroaryl; and R^(9A) can be anoptionally substituted N-linked amino acid or an optionally substitutedN-linked amino acid ester derivative. In some embodiments, R^(9A) can bean amino acid selected from alanine, asparagine, aspartate, cysteine,glutamate, glutamine, glycine, proline, serine, tyrosine, arginine,histidine, isoleucine, leucine, lysine, methionine, phenylalanine,threonine, tryptophan, valine and ester derivatives thereof. The aminoacid can have various stereochemical configurations. For example, theamino acid can be racemic, an L-stereoisomer, a D-stereoisomer or amixture of L- and D-stereoisomers that is enriched in one or the otherof the stereoisomers. In an embodiment, the L-stereoisomer content ofthe amino acid is at least about 90%, at least about 95%, or at leastabout 99%, by weight based on the mixture of L- and D-stereoisomers.Examples of an optionally substituted N-linked amino acid esterderivatives include optionally substituted versions of the following:alanine isopropyl ester, alanine cyclohexyl ester, alanine neopentylester, valine isopropyl ester and leucine isopropyl ester. In someembodiments, R^(9A) can have the structure

wherein R^(33A) can be selected from hydrogen, an optionally substitutedC₁₋₆-alkyl, an optionally substituted C₃₋₆ cycloalkyl, an optionallysubstituted aryl, an optionally substituted aryl(C₁₋₆ alkyl) and anoptionally substituted haloalkyl; R^(34A) can be selected from hydrogen,an optionally substituted C₁₋₆ alkyl, an optionally substituted C₁₋₆haloalkyl, an optionally substituted C₃₋₆ cycloalkyl, an optionallysubstituted C₆ aryl, an optionally substituted C₁₀ aryl and anoptionally substituted aryl(C₁₋₆ alkyl); and R^(35A) can be hydrogen oran optionally substituted C₁₋₄-alkyl; or R^(34A) and R^(35A) can betaken together to form an optionally substituted C₃₋₆ cycloalkyl. Theamino acid portion of the optionally substituted N-linked amino acidester derivatives can have the various stereochemical configurationsthat are described above for amino acids. In an embodiment, R^(9A) is

In an embodiment, R^(33A) is C₁₋₆ alkyl.

When R^(34A) is substituted, R^(34A) can be substituted with one or moresubstituents selected from N-amido, mercapto, alkylthio, an optionallysubstituted aryl, hydroxy, an optionally substituted heteroaryl,O-carboxy and amino. In some embodiments, R^(34A) can be anunsubstituted C₁₋₆-alkyl, such as those described herein. In someembodiments, R^(34A) can be hydrogen. In other embodiments, R^(34A) canbe methyl. In some embodiments, R^(33A) can be an optionally substitutedC₁₋₆ alkyl. Examples of optionally substituted C₁₋₆-alkyls includeoptionally substituted variants of the following: methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl (branched andstraight-chained) and hexyl (branched and straight-chained). In someembodiments, R^(33A) can be methyl or isopropyl. In some embodiments,R^(33A) can be ethyl or neopentyl. In other embodiments, R^(33A) can bean optionally substituted C₃₋₆ cycloalkyl. Examples of optionallysubstituted C₃₋₆ cycloalkyl include optionally substituted variants ofthe following: cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. Inan embodiment, R^(33A) can be an optionally substituted cyclohexyl. Instill other embodiments, R^(33A) can be an optionally substituted aryl,such as phenyl and naphthyl. In yet still other embodiments, R^(33A) canbe an optionally substituted aryl(C₁₋₆ alkyl). In some embodiments,R^(33A) can be an optionally substituted benzyl. In some embodiments,R^(33A) can be an optionally substituted C₁₋₆ haloalkyl, for example,CF₃. In some embodiments, R^(35A) can be hydrogen. In other embodiments,R^(35A) can be an optionally substituted C₁₋₄-alkyl, such as methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl. In anembodiment, R^(35A) can be methyl. In some embodiments, R^(34A) andR^(35A) can be taken together to form an optionally substituted C₃₋₆cycloalkyl. Examples of optionally substituted C₃₋₆ cycloalkyl includeoptionally substituted variants of the following: cyclopropyl,cyclobutyl, cyclopentyl, and cyclohexyl. Depending on the groups thatare selected for R^(34A) and R^(35A), the carbon to which R^(34A) andR^(35A) are attached may be a chiral center. In some embodiment, thecarbon to which R^(34A) and R^(35A) are attached may be a (R)-chiralcenter. In other embodiments, the carbon to which R^(34A) and R^(35A)are attached may be a (S)-chiral center.

In some embodiments, when R^(5A) is

Z^(2A) can be O (oxygen). In other embodiments, when R^(5A) is

Z^(2A) can be S (sulfur). In some embodiments, when R^(5A) is

a compound of Formula (I) can be a phosphoramidate prodrug, such as anaryl phosphoramidate prodrug.

In some embodiments, R^(5A) can be

In some embodiments, R^(10A) and R^(11A) can be both an optionallysubstituted N-linked amino acid or an optionally substituted N-linkedamino acid ester derivative. In some embodiments, one or both of R^(10A)and R^(11A) can be an amino acid independently selected from alanine,asparagine, aspartate, cysteine, glutamate, glutamine, glycine, proline,serine, tyrosine, arginine, histidine, isoleucine, leucine, lysine,methionine, phenylalanine, threonine, tryptophan, valine and esterderivatives thereof. The amino acid can have various stereochemicalconfigurations. For example, the amino acid can be racemic, anL-stereoisomer, a D-stereoisomer or a mixture of L- and D-stereoisomersthat is enriched in one or the other of the stereoisomers. In anembodiment, the L-stereoisomer content of the amino acid is at leastabout 90%, at least about 95%, or at least about 99%, by weight based onthe mixture of L- and D-stereoisomers. In some embodiments, R^(10A) andR^(11A) can be an optionally substituted version of the following:alanine isopropyl ester, alanine cyclohexyl ester, alanine neopentylester, valine isopropyl ester and leucine isopropyl ester. In someembodiments, R^(10A) and R^(11A) can independently have the structure

wherein R^(36A) can be selected from hydrogen, an optionally substitutedC₁₋₆-alkyl, an optionally substituted C₃₋₆ cycloalkyl, an optionallysubstituted aryl, an optionally substituted aryl(C₁₋₆ alkyl) and anoptionally substituted haloalkyl; R^(37A) can be selected from hydrogen,an optionally substituted C₁₋₆ alkyl, an optionally substituted C₁₋₆haloalkyl, an optionally substituted C₃₋₆ cycloalkyl, an optionallysubstituted C₆ aryl, an optionally substituted C₁₀ aryl and anoptionally substituted aryl(C₁₋₆ alkyl); and R^(38A) can be hydrogen oran optionally substituted C₁₋₄-alkyl; or R^(37A) and R^(38A) can betaken together to form an optionally substituted C₃₋₆ cycloalkyl.

When R^(37A) is substituted, R^(37A) can be substituted with one or moresubstituents selected from N-amido, mercapto, alkylthio, an optionallysubstituted aryl, hydroxy, an optionally substituted heteroaryl,O-carboxy and amino. In some embodiments, R^(37A) can be anunsubstituted C₁₋₆-alkyl, such as those described herein. In someembodiments, R^(37A) can be hydrogen. In other embodiments, R^(37A) canbe methyl. In some embodiments, R^(36A) can be an optionally substitutedC₁₋₆ alkyl. Examples of optionally substituted C₁₋₆-alkyls includeoptionally substituted variants of the following: methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl (branched andstraight-chained) and hexyl (branched and straight-chained). In someembodiments, R^(36A) can be methyl or isopropyl. In some embodiments,R^(36A) can be ethyl or neopentyl. In other embodiments, R^(36A) can bean optionally substituted C₃₋₆ cycloalkyl. Examples of optionallysubstituted C₃₋₆ cycloalkyl include optionally substituted variants ofthe following: cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. Inan embodiment, R^(36A) can be an optionally substituted cyclohexyl. Instill other embodiments, R^(36A) can be an optionally substituted aryl,such as phenyl and naphthyl. In yet still other embodiments, R^(36A) canbe an optionally substituted aryl(C₁₋₆ alkyl). In some embodiments,R^(36A) can be an optionally substituted benzyl. In some embodiments,R^(36A) can be an optionally substituted C₁₋₆ haloalkyl, for example,CF₃. In some embodiments, R^(38A) can be hydrogen. In other embodiments,R^(38A) can be an optionally substituted C₁₋₄-alkyl, such as methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl. In anembodiment, R^(38A) can be methyl. In some embodiments, R^(37A) andR^(38A) can be taken together to form an optionally substituted C₃₋₆cycloalkyl. Examples of optionally substituted C₃₋₆ cycloalkyl includeoptionally substituted variants of the following: cyclopropyl,cyclobutyl, cyclopentyl, and cyclohexyl. Depending on the groups thatare selected for R^(37A) and R^(38A), the carbon to which R^(37A) andR^(38A) are attached may be a chiral center. In some embodiment, thecarbon to which R^(37A) and R^(38A) are attached may be a (R)-chiralcenter. In other embodiments, the carbon to which R^(37A) and R^(38A)are attached may be a (S)-chiral center.

Examples of suitable

groups include the following:

In some embodiments, R^(10A) and R^(11A) can be the same. In someembodiments, R^(10A) and R^(11A) can be different.

In some embodiments, Z^(3A) can be O (oxygen). In other embodiments,Z^(3A) can be S (sulfur). In some embodiments, when R^(5A) is

a compound of Formula (I) can be a phosphonic diamide prodrug.

Those skilled in the art understand that when R^(8A), R^(9A), and/orR^(10A) are absent, the associated oxygen(s) will have a negativecharge. For example, when R^(8A) is absent, the oxygen associated withR^(8A) will have a negative charge. The variable m in R^(7A) can be 0, 1or 2. Thus, in an embodiment, R^(7A) can be a monophosphate (m=0), inwhich case R^(10A) is absent. In another embodiment, R^(7A) can be adiphosphate (m=1). In yet another embodiment, R^(7A) can be atriphosphate (m=2).

By neutralizing the charge on the phosphorus moiety of the compounds ofFormulae (I), penetration of the cell membrane may be facilitated as aresult of the increased lipophilicity of the compound. Once absorbed andtaken inside the cell, the groups attached to the phosphorus can beeasily removed by esterases, proteases and/or other enzymes. In someembodiments, the groups attached to the phosphorus can be removed bysimple hydrolysis. Inside the cell, the phosphate thus released may thenbe metabolized by cellular enzymes to the diphosphate or the activetriphosphate. Furthermore, in some embodiments, varying the substituentson a compound described herein, such as a compound of Formula (I), or apharmaceutically acceptable salt of any of the foregoing, can helpmaintain the efficacy of the compound by reducing undesirable effects.

In some embodiments, R^(5A) can be hydrogen. In some embodiments, R^(5A)can be an optionally substituted acyl. In other embodiments, R^(5A) canbe —C(═O)R^(39A) wherein R^(39A) can be selected from an optionallysubstituted C₁₋₁₂ alkyl, an optionally substituted C₂₋₁₂ alkenyl, anoptionally substituted C₂₋₁₂ alkynyl, an optionally substituted C₃₋₈cycloalkyl, an optionally substituted C₅₋₈ cycloalkenyl, an optionallysubstituted C₆₋₁₀ aryl, an optionally substituted heteroaryl, anoptionally substituted heterocyclyl, an optionally substituted aryl(C₁₋₆alkyl), an optionally substituted heteroaryl(C₁₋₆ alkyl) and anoptionally substituted heterocyclyl(C₁₋₆ alkyl). In some embodiments,R^(39A) can be a substituted C₁₋₁₂ alkyl. In other embodiments, R^(39A)can be an unsubstituted C₁₋₁₂ alkyl.

In still other embodiments, R^(5A) can be an optionally substitutedO-linked amino acid. Examples of suitable O-linked amino acids includealanine, asparagine, aspartate, cysteine, glutamate, glutamine, glycine,proline, serine, tyrosine, arginine, histidine, isoleucine, leucine,lysine, methionine, phenylalanine, threonine, tryptophan and valine.Additional examples of suitable amino acids include, but are not limitedto, ornithine, hypusine, 2-aminoisobutyric acid, dehydroalanine,gamma-aminobutyric acid, citrulline, beta-alanine, alpha-ethyl-glycine,alpha-propyl-glycine and norleucine. In some embodiments, the O-linkedamino acid can be selected such that —OR^(5A) has the structure

wherein R^(40A) can be selected from hydrogen, an optionally substitutedC₁₋₆ alkyl, an optionally substituted C₁₋₆ haloalkyl, an optionallysubstituted C₃₋₆ cycloalkyl, an optionally substituted C₆ aryl, anoptionally substituted C₁₀ aryl and an optionally substituted aryl(C₁₋₆alkyl); and R^(41A) can be hydrogen or an optionally substitutedC₁₋₄-alkyl; or R^(40A) and R^(41A) can be taken together to form anoptionally substituted C₃₋₆ cycloalkyl.

When R^(40A) is substituted, R^(40A) can be substituted with one or moresubstituents selected from N-amido, mercapto, alkylthio, an optionallysubstituted aryl, hydroxy, an optionally substituted heteroaryl,O-carboxy and amino. In some embodiments, R^(40A) can be anunsubstituted C₁₋₆-alkyl, such as those described herein. In someembodiments, R^(40A) can be hydrogen. In other embodiments, R^(40A) canbe methyl. In some embodiments, R^(41A) can be hydrogen. In otherembodiments, R^(41A) can be an optionally substituted C₁₋₄-alkyl, suchas methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl.In an embodiment, R^(41A) can be methyl. Depending on the groups thatare selected for R^(40A) and R^(41A), the carbon to which R^(40A) andR^(41A) are attached may be a chiral center. In some embodiment, thecarbon to which R^(40A) and R^(41A) are attached may be a (R)-chiralcenter. In other embodiments, the carbon to which R^(40A) and R^(41A)are attached may be a (S)-chiral center.

Examples of suitable

include the following:

In various embodiments a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof, is a panviral compound. As used herein in thiscontext, the term “panviral” refers to a compound (e.g., a nucleosideanalog or a nucleotide analog) that exhibits pharmaceuticallysignificant activity against viruses in two or more families of viruses.The degree to which a compound exhibits pharmaceutically significantactivity can be determined by using a validated assay that isappropriate for the virus being tested. Such assay methods are known tothose skilled in the art and include the assay methods described in theExamples below. In general, a compound of Formula (I), or apharmaceutically acceptable salt thereof, is considered to be panviralif it exhibits an EC₅₀ and/or IC₅₀ value of 100 μM or less in at leastone assay for a virus in a first virus family and also exhibits an EC₅₀and/or IC₅₀ value of 100 μM or less in at least one assay for a virus ina second virus family that is different from the first family. It willbe apparent to those skilled in the art that compounds having greateractivity are also considered panviral. For example, a compound ofFormula (I), or a pharmaceutically acceptable salt thereof, is alsoconsidered to be panviral if it exhibits an EC₅₀ and/or IC₅₀ value of 10μM or less in at least one assay for a virus in a first virus family andalso exhibits an EC₅₀ and/or IC₅₀ value of 100 μM or less in at leastone assay for a virus in a second virus family that is different fromthe first family.

In various embodiments a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof, is a low toxicity compound. As used herein inthis context, the term “low toxicity” refers to a compound (e.g., anucleoside analog or a nucleotide analog) that exhibits pharmaceuticallyinsignificant toxicity when tested using a validated toxicity assay thatis appropriate for the virus being tested. Such assay methods are knownto those skilled in the art and include the assay methods described inthe Examples below. In general, a compound of Formula (I), or apharmaceutically acceptable salt thereof, is considered to exhibitpharmaceutically insignificant toxicity if it exhibits a 50% cytotoxicconcentration (CC₅₀) value of 10 μM or more. It will be apparent tothose skilled in the art that less toxic compounds are also consideredlow toxicity. For example, a compound is also considered to exhibitpharmaceutically insignificant toxicity if it exhibits a CC₅₀ value of100 μM or more.

In various embodiments a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof, is a low toxicity panviral nucleoside analog.As used herein in this context, the term “low toxicity panviral” refersto a compound of Formula (I), or a pharmaceutically acceptable saltthereof, that is both low toxicity and panviral, as described above.

Synthesis

Compounds of Formula (I), or a pharmaceutically acceptable salt thereofmay be prepared in various ways, including those known to those skilledin the art. The synthetic routes described herein are illustrative onlyand are not intended, nor are they to be construed, to limit the scopeof the claims in any manner whatsoever. Those skilled in the art will beable to recognize modifications of the disclosed syntheses and to devisealternate routes based on the disclosures herein; all such modificationsand alternate routes are within the scope of the claims. Examples ofmethods are described in the Examples below.

Pharmaceutical Compositions

Some embodiments described herein relate to a pharmaceuticalcomposition, that can include an effective amount of one or morecompounds described herein (e.g., a compound of Formula (I), or apharmaceutically acceptable salt thereof) and a pharmaceuticallyacceptable carrier, diluent, excipient or combination thereof. In someembodiments, the pharmaceutical composition can include a singlediastereomer of a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof, (for example, a single diastereomer present inthe pharmaceutical composition at a concentration of greater than 99%compared to the total concentration of the other diastereomers). Inother embodiments, the pharmaceutical composition can include a mixtureof diastereomers of a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof. For example, the pharmaceutical composition caninclude a concentration of one diastereomerof >50%, >60%, >70%, >80%, >90%, >95%, or >98%, as compared to the totalconcentration of the other diastereomers. In some embodiments, thepharmaceutical composition includes a 1:1 mixture of two diastereomersof a compound of Formula (I), or a pharmaceutically acceptable saltthereof.

The term “pharmaceutical composition” refers to a mixture of one or morecompounds disclosed herein with other chemical components, such asdiluents or carriers. The pharmaceutical composition facilitatesadministration of the compound to an organism. Pharmaceuticalcompositions can also be obtained by reacting compounds with inorganicor organic acids such as hydrochloric acid, hydrobromic acid, sulfuricacid, nitric acid, phosphoric acid, methanesulfonic acid, ethanesulfonicacid, p-toluenesulfonic acid and salicylic acid. Pharmaceuticalcompositions will generally be tailored to the specific intended routeof administration. A pharmaceutical composition is suitable for humanand/or veterinary applications.

The term “physiologically acceptable” defines a carrier, diluent orexcipient that does not abrogate the biological activity and propertiesof the compound.

As used herein, a “carrier” refers to a compound that facilitates theincorporation of a compound into cells or tissues. For example, withoutlimitation, dimethyl sulfoxide (DMSO) is a commonly utilized carrierthat facilitates the uptake of many organic compounds into cells ortissues of a subject.

As used herein, a “diluent” refers to an ingredient in a pharmaceuticalcomposition that lacks pharmacological activity but may bepharmaceutically necessary or desirable. For example, a diluent may beused to increase the bulk of a potent drug whose mass is too small formanufacture and/or administration. It may also be a liquid for thedissolution of a drug to be administered by injection, ingestion orinhalation. A common form of diluent in the art is a buffered aqueoussolution such as, without limitation, phosphate buffered saline thatmimics the composition of human blood.

As used herein, an “excipient” refers to an inert substance that isadded to a pharmaceutical composition to provide, without limitation,bulk, consistency, stability, binding ability, lubrication,disintegrating ability etc., to the composition. A “diluent” is a typeof excipient.

The pharmaceutical compositions described herein can be administered toa human patient per se, or in pharmaceutical compositions where they aremixed with other active ingredients, as in combination therapy, orcarriers, diluents, excipients or combinations thereof. Properformulation is dependent upon the route of administration chosen.Techniques for formulation and administration of the compounds describedherein are known to those skilled in the art.

The pharmaceutical compositions disclosed herein may be manufactured ina manner that is itself known, e.g., by means of conventional mixing,dissolving, granulating, dragee-making, levigating, emulsifying,encapsulating, entrapping or tableting processes. Additionally, theactive ingredients are contained in an amount effective to achieve itsintended purpose. Many of the compounds used in the pharmaceuticalcombinations disclosed herein may be provided as salts withpharmaceutically compatible counterions.

Multiple techniques of administering a compound exist in the artincluding, but not limited to, oral, rectal, topical, aerosol, injectionand parenteral delivery, including intramuscular, subcutaneous,intravenous, intramedullary injections, intrathecal, directintraventricular, intraperitoneal, intranasal and intraocularinjections.

One may also administer the compound in a local rather than systemicmanner, for example, via injection of the compound directly into theinfected area, often in a depot or sustained release formulation.Furthermore, one may administer the compound in a targeted drug deliverysystem, for example, in a liposome coated with a tissue-specificantibody. The liposomes will be targeted to and taken up selectively bythe organ.

The compositions may, if desired, be presented in a pack or dispenserdevice which may contain one or more unit dosage forms containing theactive ingredient. The pack may for example comprise metal or plasticfoil, such as a blister pack. The pack or dispenser device may beaccompanied by instructions for administration. The pack or dispensermay also be accompanied with a notice associated with the container inform prescribed by a governmental agency regulating the manufacture,use, or sale of pharmaceuticals, which notice is reflective of approvalby the agency of the form of the drug for human or veterinaryadministration. Such notice, for example, may be the labeling approvedby the U.S. Food and Drug Administration for prescription drugs, or theapproved product insert. Compositions that can include a compounddescribed herein formulated in a compatible pharmaceutical carrier mayalso be prepared, placed in an appropriate container, and labeled fortreatment of an indicated condition.

In an embodiment, a panviral treatment as described elsewhere herein isformulated for administration to a subject having a viral infection. Forexample, those skilled in the art appreciate that, depending on the typeof viral infection, it may be more advantageous to administer a panviraltreatment that has been formulated in a particular manner, e.g., in theform of a pharmaceutical composition that facilitates administration bya particular route (e.g., oral, aerosol, injection, etc.) and/or withappropriate labeling for treatment of the condition for which it isindicated. An embodiment provides a panviral treatment formulated foradministration to a subject having a Picornaviridae, Flaviviridae,Filoviridae, Pneumoviridae and/or Coronaviridae viral infection.

Methods of Use

Some embodiments disclosed herein relate to a method of treating and/orameliorating a Picornaviridae viral infection that can includeadministering to a subject infected with the Picornaviridae virus aneffective amount of one or more compounds described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof),or a pharmaceutical composition that includes a compound describedherein (such as a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof). Other embodiments disclosed herein relate to amethod of treating and/or ameliorating a Picornaviridae viral infectionthat can include administering to a subject identified as suffering fromthe viral infection an effective amount of one or more compoundsdescribed herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes a compound described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof).

Some embodiments described herein relate to methods of using one or morecompounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), in the manufacture of amedicament for ameliorating and/or treating a Picornaviridae viralinfection that can include administering to a subject infected with thePicornaviridae virus an effective amount of one or more compoundsdescribed herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof). Still other embodimentsdescribed herein relate to one or more compounds described herein (suchas a compound of Formula (I), or a pharmaceutically acceptable saltthereof) that can be used for ameliorating and/or treating aPicornaviridae viral infection by administering to a subject infectedwith the Picornaviridae virus an effective amount of one or morecompounds described herein.

Some embodiments disclosed herein relate to methods of amelioratingand/or treating a Picornaviridae viral infection that can includecontacting a cell infected with the Picornaviridae virus with aneffective amount of one or more compounds described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof),or a pharmaceutical composition that includes one or more compoundsdescribed herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof). Other embodiments describedherein relate to using one or more compounds described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof),in the manufacture of a medicament for ameliorating and/or treating aPicornaviridae viral infection that can include contacting a cellinfected with the Picornaviridae virus with an effective amount of saidcompound(s). Still other embodiments described herein relate to one ormore compounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), that can be used forameliorating and/or treating a Picornaviridae viral infection bycontacting a cell infected with the Picornaviridae virus with aneffective amount of said compound(s).

Some embodiments disclosed herein relate to methods of inhibitingreplication of a Picornaviridae virus that can include contacting a cellinfected with the Picornaviridae virus with an effective amount of oneor more compounds described herein (such as a compound of Formula (I),or a pharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes one or more compounds described herein (suchas a compound of Formula (I), or a pharmaceutically acceptable saltthereof). Other embodiments described herein relate to using one or morecompounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), in the manufacture of amedicament for inhibiting replication of a Picornaviridae virus that caninclude contacting a cell infected with the Picornaviridae virus with aneffective amount of said compound(s). Still other embodiments describedherein relate to a compound described herein (such as a compound ofFormula (I), or a pharmaceutically acceptable salt thereof), that can beused for inhibiting replication of a Picornaviridae virus by contactinga cell infected with the Picornaviridae virus with an effective amountof said compound(s). In some embodiments, a compound of Formula (I), ora pharmaceutically acceptable salt thereof, can inhibit a RNA dependentRNA polymerase of a Picornaviridae virus, and thus, inhibit thereplication of RNA. In some embodiments, a polymerase of aPicornaviridae virus can be inhibited by contacting a cell infected withthe Picornaviridae virus with a compound described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof).

In some embodiments, the Picornaviridae virus can be selected from anAphthovirus, an Enterovirus, a Rhinovirus, a Hepatovirus and aParechovirus. In some embodiments, a compound described herein (forexample, a compound of Formula (I), or a pharmaceutically acceptablesalt thereof) can ameliorate and/or treat a Rhinovirus infection. Forexample, by administering an effective amount of a compound of Formula(I), or a pharmaceutically acceptable salt thereof, to a subjectinfected with the Rhinovirus and/or by contacting a cell infected withthe Rhinovirus. In some embodiments, a compound described herein (forexample, a compound of Formula (I), or a pharmaceutically acceptablesalt thereof) can inhibit replication of a Rhinovirus. In someembodiments, a compound of Formula (I), or a pharmaceutically acceptablesalt thereof, can be effective against a Rhinovirus, and therebyameliorate one or more symptoms of a Rhinovirus infection.

Various indicators for determining the effectiveness of a method fortreating a Picornaviridae viral infection are known to those skilled inthe art. Example of suitable indicators include, but are not limited to,a reduction in viral load, a reduction in viral replication, a reductionin time to seroconversion (virus undetectable in patient serum), areduction of morbidity or mortality in clinical outcomes, and/or otherindicator(s) of disease response. Further indicators include one or moreoverall quality of life health indicators, such as reduced illnessduration, reduced illness severity, reduced time to return to normalhealth and normal activity, and reduced time to alleviation of one ormore symptoms. In some embodiments, a compound of Formula (I), or apharmaceutically acceptable salt thereof, can result in the reduction,alleviation or positive indication of one or more of the aforementionedindicators compared to an untreated subject. Effects/symptoms of aPicornaviridae viral infection are described herein, and include, butare not limited to, fever, blisters, rash, meningitis, conjunctivitis,acute hemorrhagic conjunctivitis (AHC), sore throat, nasal congestion,runny nose, sneezing, coughing, loss of appetite, muscle aches,headache, fatigue, nausea, jaundice, encephalitis, herpangina,myocarditis, pericarditis, meningitis, Bornholm disease, myalgia, nasalcongestion, muscle weakness, loss of appetite, fever, vomiting,abdominal pain, abdominal discomfort, dark urine and muscle pain.

Some embodiments disclosed herein relate to a method of treating and/orameliorating a Flaviviridae viral infection that can includeadministering to a subject infected with the Flaviviridae virus aneffective amount of one or more compounds described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof),or a pharmaceutical composition that includes a compound describedherein (such as a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof). Other embodiments disclosed herein relate to amethod of treating and/or ameliorating a Flaviviridae viral infectionthat can include administering to a subject an effective amount of oneor more compounds described herein (such as a compound of Formula (I),or a pharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes a compound described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof).Some embodiments described herein relate to methods of using one or morecompounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), in the manufacture of amedicament for ameliorating and/or treating a Flaviviridae viralinfection that can include administering an effective amount of one ormore compounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof). Still other embodimentsdescribed herein relate to one or more compounds described herein (suchas a compound of Formula (I), or a pharmaceutically acceptable saltthereof) that can be used for ameliorating and/or treating aFlaviviridae viral infection by administering to a subject an effectiveamount of one or more compounds described herein.

Some embodiments disclosed herein relate to methods of amelioratingand/or treating a Flaviviridae viral infection that can includecontacting a cell infected with the Flaviviridae virus with an effectiveamount of one or more compounds described herein (such as a compound ofFormula (I), or a pharmaceutically acceptable salt thereof), or apharmaceutical composition that includes one or more compounds describedherein (such as a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof). Other embodiments described herein relate tousing one or more compounds described herein (such as a compound ofFormula (I), or a pharmaceutically acceptable salt thereof), in themanufacture of a medicament for ameliorating and/or treating aFlaviviridae viral infection that can include contacting a cell infectedwith the Flaviviridae virus with an effective amount of saidcompound(s). Still other embodiments described herein relate to one ormore compounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), that can be used forameliorating and/or treating a Flaviviridae viral infection bycontacting a cell infected with the Flaviviridae virus with an effectiveamount of said compound(s).

Some embodiments disclosed herein relate to methods of inhibitingreplication of a Flaviviridae virus that can include contacting a cellinfected with the Flaviviridae virus with an effective amount of one ormore compounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes one or more compounds described herein (suchas a compound of Formula (I), or a pharmaceutically acceptable saltthereof). Other embodiments described herein relate to using one or morecompounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), in the manufacture of amedicament for inhibiting replication of a Flaviviridae virus that caninclude contacting a cell infected with the Flaviviridae virus with aneffective amount of said compound(s). Still other embodiments describedherein relate to a compound described herein (such as a compound ofFormula (I), or a pharmaceutically acceptable salt thereof), that can beused for inhibiting replication of a Flaviviridae virus by contacting acell infected with the Flaviviridae virus with an effective amount ofsaid compound(s). In some embodiments, a polymerase of a Flaviviridaevirus can be inhibited by contacting a cell infected with theFlaviviridae virus with a compound described herein (such as a compoundof Formula (I), or a pharmaceutically acceptable salt thereof), andthereby, inhibit the replication of RNA.

Some embodiments disclosed herein relate to methods of amelioratingand/or treating a HCV infection that can include contacting a cellinfected with HCV with an effective amount of one or more compoundsdescribed herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes one or more compounds described herein (suchas a compound of Formula (I), or a pharmaceutically acceptable saltthereof). Other embodiments described herein relate to methods of usingone or more compounds described herein (such as a compound of Formula(I), or a pharmaceutically acceptable salt thereof), in the manufactureof a medicament for ameliorating and/or treating a HCV infection thatcan include contacting a cell infected with HCV with an effective amountof said compound(s). Still other embodiments described herein relate toone or more compounds described herein (such as a compound of Formula(I), or a pharmaceutically acceptable salt thereof), that can be usedfor ameliorating and/or treating a HCV infection by contacting a cellinfected with HCV with an effective amount of said compound(s).

Some embodiments described herein relate to a method of inhibiting NS5Bpolymerase activity that can include contacting a cell infected withhepatitis C virus with an effective amount of a compound of Formula (I),or a pharmaceutically acceptable salt thereof. As noted above, NS5B isbelieved to be an RNA-dependent RNA polymerase involved in thereplication of HCV RNA. Some embodiments described herein relate to amethod of inhibiting NS5B polymerase activity that can includeadministering to a subject infected with hepatitis C virus an effectiveamount of a compound of Formula (I), or a pharmaceutically acceptablesalt thereof. In some embodiments, a compound of Formula (I), or apharmaceutically acceptable salt thereof, can inhibit a RNA dependentRNA polymerase, and thus, inhibit the replication of HCV RNA. In someembodiments, a compound of Formula (I), or a pharmaceutically acceptablesalt thereof, can inhibit a HCV polymerase (for example, NS5Bpolymerase).

Some embodiments described herein relate to a method of treating acondition selected from liver fibrosis, liver cirrhosis and liver cancerin a subject suffering from one or more of the aforementioned liverconditions that can include administering to the subject an effectiveamount of a compound or a pharmaceutical composition described herein(for example, a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof), wherein the liver condition is caused by a HCVinfection. Some embodiments described herein relate to a method ofincreasing liver function in a subject having a HCV infection that caninclude administering to the subject an effective amount of a compoundor a pharmaceutical composition described herein (for example, acompound of Formula (I), or a pharmaceutically acceptable salt thereof).Also contemplated is a method for reducing or eliminating furthervirus-caused liver damage in a subject having an HCV infection byadministering to the subject an effective amount of a compound or apharmaceutical composition described herein (for example, a compound ofFormula (I), or a pharmaceutically acceptable salt thereof). In someembodiments, this method can include slowing or halting the progressionof liver disease. In other embodiments, the course of the disease can bereversed, and stasis or improvement in liver function is contemplated.In some embodiments, liver fibrosis, liver cirrhosis and/or liver cancercan be treated; liver function can be increased; virus-caused liverdamage can be reduced or eliminated; progression of liver disease can beslowed or halted; the course of the liver disease can be reversed and/orliver function can be improved or maintained by contacting a cellinfected with hepatitis C virus with an effective amount of a compounddescribed herein (for example, a compound of Formula (I), or apharmaceutically acceptable salt thereof.)

There are a variety of genotypes of HCV, and a variety of subtypeswithin each genotype. For example, at present it is known that there areeleven (numbered 1 through 11) main genotypes of HCV, although othershave classified the genotypes as 6 main genotypes. Each of thesegenotypes is further subdivided into subtypes (1a-1c; 2a-2c; 3a-3b;4a-4e; 5a; 6a; 7a-7b; 8a-8b; 9a; 10a; and 11a). In some embodiments, aneffective amount of a compound of Formula (I), or a pharmaceuticalacceptable salt thereof, or a pharmaceutical composition that includesan effective amount of a compound of Formula (I), or a pharmaceuticalacceptable salt of any of the foregoing, can be effective to treat atleast one genotype of HCV. In some embodiments, a compound describedherein (for example, a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof) can be effective to treat all 11 genotypes ofHCV. In some embodiments, a compound described herein (for example, acompound of Formula (I), or a pharmaceutically acceptable salt thereof)can be effective to treat 3 or more, 5 or more, 7 or more, or 9 or moregenotypes of HCV. In some embodiments, a compound of Formula (I), or apharmaceutical acceptable salt thereof, can be more effective against alarger number of HCV genotypes than the standard of care. In someembodiments, a compound of Formula (I), or a pharmaceutically acceptablesalt thereof, can be more effective against a particular HCV genotypethan the standard of care (such as genotype 1, 2, 3, 4, 5 and/or 6).

Various indicators for determining the effectiveness of a method fortreating a HCV infection are known to those skilled in the art. Examplesof suitable indicators include, but are not limited to, a reduction inviral load, a reduction in viral replication, a reduction in time toseroconversion (virus undetectable in patient serum), an increase in therate of sustained viral response to therapy, a reduction of morbidity ormortality in clinical outcomes, a reduction in the rate of liverfunction decrease; stasis in liver function; improvement in liverfunction; reduction in one or more markers of liver dysfunction,including alanine transaminase, aspartate transaminase, total bilirubin,conjugated bilirubin, gamma glutamyl transpeptidase and/or otherindicator of disease response. Similarly, successful therapy with aneffective amount of a compound or a pharmaceutical composition describedherein (for example, a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof) can reduce the incidence of liver cancer in HCVinfected subjects.

In some embodiments, a compound described herein (for example, acompound of Formula (I), or a pharmaceutical acceptable salt thereof)can be used to ameliorate and/or treat a Flavivirus infection. In someembodiments, a compound described herein (for example, a compound ofFormula (I), or a pharmaceutical acceptable salt thereof) can inhibitreplication of a Flavivirus.

In some embodiments, the Flavivirus can be a West Nile virus. In someembodiments, a compound described herein (for example, a compound ofFormula (I), or a pharmaceutical acceptable salt thereof) can treatand/or ameliorate a dengue virus, such as DENV-1, DENV-2, DENV-3 andDENV-4. A dengue virus infection can cause dengue hemorrhagic feverand/or dengue shock syndrome. In some embodiments, a compound describedherein (for example, a compound of Formula (I), or a pharmaceuticalacceptable salt thereof) can treat and/or ameliorate dengue hemorrhagicfever and/or dengue shock syndrome. In some embodiments, the Flaviviruscan be yellow fever virus. In yet still other embodiments, theFlavivirus can be an encephalitis virus from within the Flavivirusgenus. Examples of encephalitis viruses include, but are not limited to,Japanese encephalitis virus, St. Louis encephalitis virus and tick borneencephalitis. In some embodiments, the Flavivirus can be a Zika virus.

Some embodiments disclosed herein relate to a method of treating and/orameliorating a Filoviridae viral infection that can includeadministering to a subject infected with the Filoviridae virus aneffective amount of one or more compounds described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof),or a pharmaceutical composition that includes a compound describedherein (such as a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof). Other embodiments disclosed herein relate to amethod of treating and/or ameliorating a Filoviridae viral infectionthat can include administering to a subject identified as suffering fromthe viral infection an effective amount of one or more compoundsdescribed herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes a compound described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof).

Some embodiments described herein relate to methods of using one or morecompounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), in the manufacture of amedicament for ameliorating and/or treating a Filoviridae viralinfection that can include administering to a subject infected with theFiloviridae virus an effective amount of one or more compounds describedherein (such as a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof). Still other embodiments described hereinrelate to one or more compounds described herein (such as a compound ofFormula (I), or a pharmaceutically acceptable salt thereof) that can beused for ameliorating and/or treating a Filoviridae viral infection byadministering to a subject infected with the Filoviridae virus aneffective amount of one or more compounds described herein.

Some embodiments disclosed herein relate to methods of amelioratingand/or treating a Filoviridae viral infection that can includecontacting a cell infected with the Filoviridae virus with an effectiveamount of one or more compounds described herein (such as a compound ofFormula (I), or a pharmaceutically acceptable salt thereof), or apharmaceutical composition that includes one or more compounds describedherein (such as a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof). Other embodiments described herein relate tousing one or more compounds described herein (such as a compound ofFormula (I), or a pharmaceutically acceptable salt thereof), in themanufacture of a medicament for ameliorating and/or treating aFiloviridae viral infection that can include contacting a cell infectedwith the Filoviridae virus with an effective amount of said compound(s).Still other embodiments described herein relate to one or more compoundsdescribed herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), that can be used forameliorating and/or treating a Filoviridae viral infection by contactinga cell infected with the Filoviridae virus with an effective amount ofsaid compound(s).

Some embodiments disclosed herein relate to methods of inhibitingreplication of a Filoviridae virus that can include contacting a cellinfected with the Filoviridae virus with an effective amount of one ormore compounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes one or more compounds described herein (suchas a compound of Formula (I), or a pharmaceutically acceptable saltthereof). Other embodiments described herein relate to using one or morecompounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), in the manufacture of amedicament for inhibiting replication of a Filoviridae virus that caninclude contacting a cell infected with the Filoviridae virus with aneffective amount of said compound(s). Still other embodiments describedherein relate to a compound described herein (such as a compound ofFormula (I), or a pharmaceutically acceptable salt thereof), that can beused for inhibiting replication of a Filoviridae virus by contacting acell infected with the Filoviridae virus with an effective amount ofsaid compound(s). In some embodiments, a compound of Formula (I), or apharmaceutically acceptable salt thereof, can inhibit a RNA dependentRNA polymerase of a Filoviridae virus, and thus, inhibit the replicationof RNA. In some embodiments, a polymerase of a Filoviridae virus can beinhibited by contacting a cell infected with the Filoviridae virus witha compound described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof).

In some embodiments, a compound described herein (for example, acompound of Formula (I), or a pharmaceutical acceptable salt thereof)can be used to ameliorate and/or treat a Filoviridae viral infection. Insome embodiments, a compound described herein (for example, a compoundof Formula (I), or a pharmaceutical acceptable salt thereof) can inhibitreplication of a Filovirus.

In some embodiments, the Filoviridae virus can be selected from anEbolavirus, a Marburgvirus and a Cuevavirus. In some embodiments, acompound described herein (for example, a compound of Formula (I), or apharmaceutically acceptable salt thereof) can ameliorate and/or treat anEbolavirus infection. For example, by administering an effective amountof a compound of Formula (I), or a pharmaceutically acceptable saltthereof, to a subject infected with the Ebolavirus and/or by contactinga cell infected with the Ebolavirus. In some embodiments, a compounddescribed herein (for example, a compound of Formula (I), or apharmaceutically acceptable salt thereof) can inhibit replication of anEbolavirus. In some embodiments, a compound of Formula (I), or apharmaceutically acceptable salt thereof, can be effective against anEbolavirus, and thereby ameliorate one or more symptoms of an Ebolavirusinfection. The five recognized species of Ebolavirus are Ebola virus(EBOV), Reston ebolavirus (REBOV), Sudan ebolavirus (SEBOV), Taï Forestebolavirus (TAFV) and Bundibugyo ebolavirus (BEBOV). The two recognizedspecies of Marburgvirus are Marburg virus (MARV) and Ravn virus (RAVV).

Some embodiments disclosed herein relate to a method of treating and/orameliorating a Pneumoviridae viral infection that can includeadministering to a subject infected with the Pneumoviridae virus aneffective amount of one or more compounds described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof),or a pharmaceutical composition that includes a compound describedherein (such as a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof). Other embodiments disclosed herein relate to amethod of treating and/or ameliorating a Pneumoviridae viral infectionthat can include administering to a subject identified as suffering fromthe viral infection an effective amount of one or more compoundsdescribed herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes a compound described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof).

Some embodiments described herein relate to methods of using one or morecompounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), in the manufacture of amedicament for ameliorating and/or treating a Pneumoviridae viralinfection that can include administering to a subject infected with thePneumoviridae virus an effective amount of one or more compoundsdescribed herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof). Still other embodimentsdescribed herein relate to one or more compounds described herein (suchas a compound of Formula (I), or a pharmaceutically acceptable saltthereof) that can be used for ameliorating and/or treating aPneumoviridae viral infection by administering to a subject infectedwith the Pneumoviridae virus an effective amount of one or morecompounds described herein.

Some embodiments disclosed herein relate to methods of amelioratingand/or treating a Pneumoviridae viral infection that can includecontacting a cell infected with the Pneumoviridae virus with aneffective amount of one or more compounds described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof),or a pharmaceutical composition that includes one or more compoundsdescribed herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof). Other embodiments describedherein relate to using one or more compounds described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof),in the manufacture of a medicament for ameliorating and/or treating aPneumoviridae viral infection that can include contacting a cellinfected with the Pneumoviridae virus with an effective amount of saidcompound(s). Still other embodiments described herein relate to one ormore compounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), that can be used forameliorating and/or treating a Pneumoviridae viral infection bycontacting a cell infected with the Pneumoviridae virus with aneffective amount of said compound(s).

Some embodiments disclosed herein relate to methods of inhibitingreplication of a Pneumoviridae virus that can include contacting a cellinfected with the Pneumoviridae virus with an effective amount of one ormore compounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes one or more compounds described herein (suchas a compound of Formula (I), or a pharmaceutically acceptable saltthereof). Other embodiments described herein relate to using one or morecompounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), in the manufacture of amedicament for inhibiting replication of a Pneumoviridae virus that caninclude contacting a cell infected with the Pneumoviridae virus with aneffective amount of said compound(s). Still other embodiments describedherein relate to a compound described herein (such as a compound ofFormula (I), or a pharmaceutically acceptable salt thereof), that can beused for inhibiting replication of a Pneumoviridae virus by contacting acell infected with the Pneumoviridae virus with an effective amount ofsaid compound(s). In some embodiments, a compound of Formula (I), or apharmaceutically acceptable salt thereof, can inhibit a RNA dependentRNA polymerase of a Pneumoviridae virus, and thus, inhibit thereplication of RNA. In some embodiments, a polymerase of a Pneumoviridaevirus can be inhibited by contacting a cell infected with thePneumoviridae virus with a compound described herein (such as a compoundof Formula (I), or a pharmaceutically acceptable salt thereof).

In some embodiments, a compound described herein (for example, acompound of Formula (I), or a pharmaceutical acceptable salt thereof)can be used to ameliorate and/or treat a Pneumoviridae viral infection.In some embodiments, a compound described herein (for example, acompound of Formula (I), or a pharmaceutical acceptable salt thereof)can inhibit replication of a Pneumoviridae viral infection. In someembodiments, the Pneumovirus virus can be a Human respiratory syncytialvirus (HRSV), such as HRSV-A2, HRSV-B1 and HRSV-S2. HRSV can causerespiratory tract infections, bronchiolitis, pneumonia and severe lowerrespiratory tract disease.

Some embodiments disclosed herein relate to a method of treating and/orameliorating a Coronaviridae viral infection that can includeadministering to a subject infected with the Coronaviridae virus aneffective amount of one or more compounds described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof),or a pharmaceutical composition that includes a compound describedherein (such as a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof). Other embodiments disclosed herein relate to amethod of treating and/or ameliorating a Coronaviridae viral infectionthat can include administering to a subject identified as suffering fromthe viral infection an effective amount of one or more compoundsdescribed herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes a compound described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof).

Some embodiments described herein relate to methods of using one or morecompounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), in the manufacture of amedicament for ameliorating and/or treating a Coronaviridae viralinfection that can include administering to a subject infected with theCoronaviridae virus an effective amount of one or more compoundsdescribed herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof). Still other embodimentsdescribed herein relate to one or more compounds described herein (suchas a compound of Formula (I), or a pharmaceutically acceptable saltthereof) that can be used for ameliorating and/or treating aCoronaviridae viral infection by administering to a subject infectedwith the Coronaviridae virus an effective amount of one or morecompounds described herein.

Some embodiments disclosed herein relate to methods of amelioratingand/or treating a Coronaviridae viral infection that can includecontacting a cell infected with the Coronaviridae virus with aneffective amount of one or more compounds described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof),or a pharmaceutical composition that includes one or more compoundsdescribed herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof). Other embodiments describedherein relate to using one or more compounds described herein (such as acompound of Formula (I), or a pharmaceutically acceptable salt thereof),in the manufacture of a medicament for ameliorating and/or treating aCoronaviridae viral infection that can include contacting a cellinfected with the Coronaviridae virus with an effective amount of saidcompound(s). Still other embodiments described herein relate to one ormore compounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), that can be used forameliorating and/or treating a Coronaviridae viral infection bycontacting a cell infected with the Coronaviridae virus with aneffective amount of said compound(s).

Some embodiments disclosed herein relate to methods of inhibitingreplication of a Coronaviridae virus that can include contacting a cellinfected with the Coronaviridae virus with an effective amount of one ormore compounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), or a pharmaceuticalcomposition that includes one or more compounds described herein (suchas a compound of Formula (I), or a pharmaceutically acceptable saltthereof). Other embodiments described herein relate to using one or morecompounds described herein (such as a compound of Formula (I), or apharmaceutically acceptable salt thereof), in the manufacture of amedicament for inhibiting replication of a Coronaviridae virus that caninclude contacting a cell infected with the Coronaviridae virus with aneffective amount of said compound(s). Still other embodiments describedherein relate to a compound described herein (such as a compound ofFormula (I), or a pharmaceutically acceptable salt thereof), that can beused for inhibiting replication of a Coronaviridae virus by contacting acell infected with the Coronaviridae virus with an effective amount ofsaid compound(s). In some embodiments, a compound of Formula (I), or apharmaceutically acceptable salt thereof, can inhibit a RNA dependentRNA polymerase of a Coronaviridae virus, and thus, inhibit thereplication of RNA. In some embodiments, a polymerase of a Coronaviridaevirus can be inhibited by contacting a cell infected with theCoronaviridae virus with a compound described herein (such as a compoundof Formula (I), or a pharmaceutically acceptable salt thereof).

In some embodiments, a compound described herein (for example, acompound of Formula (I), or a pharmaceutical acceptable salt thereof)can be used ameliorate and/or treat a Coronaviridae viral infection. Insome embodiments, a compound described herein (for example, a compoundof Formula (I), or a pharmaceutical acceptable salt thereof) can inhibitreplication of a Coronaviridae viral. In some embodiments, theCoronavirus virus can be a human alpha coronavirus (HRSV) or a humanbeta coronavirus. The six coronaviruses that can infect people are:alpha coronaviruses 229E and NL63, and beta coronaviruses OC43, HKU1,SARS-CoV (the coronavirus that causes severe acute respiratory syndrome,or SARS), and MERS-CoV (the coronavirus that causes Middle EastRespiratory Syndrome, or MERS).

Various indicators for determining the effectiveness of a method fortreating a Picornaviridae, Flaviviridae, Filoviridae, Pneumoviridaeand/or Coronaviridae viral infection are known to those skilled in theart. Example of suitable indicators include, but are not limited to, areduction in viral load, a reduction in viral replication, a reductionin time to seroconversion (virus undetectable in patient serum), areduction of morbidity or mortality in clinical outcomes, and/or otherindicator(s) of disease response. Further indicators include one or moreoverall quality of life health indicators, such as reduced illnessduration, reduced illness severity, reduced time to return to normalhealth and normal activity, and reduced time to alleviation of one ormore symptoms. In some embodiments, a compound of Formula (I), or apharmaceutically acceptable salt thereof, can result in the reduction,alleviation or positive indication of one or more of the aforementionedindicators compared to a subject who is receiving the standard of careor an untreated subject.

In some embodiments, a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof, can result in a reduction in the length and/orseverity of one or more symptoms associated with a Picornaviridae,Flaviviridae, Filoviridae, Pneumoviridae and/or Coronaviridae viralinfection compared to a subject who is receiving the standard of care oran untreated subject. Table 1 provides some embodiments of thepercentage improvements obtained using a compound of Formula (I), or apharmaceutically acceptable salt thereof, as compared to the standard ofcare or an untreated subject. Examples include the following: in someembodiments, a compound of Formula (I), or a pharmaceutically acceptablesalt thereof, results in a percentage of non-responders that is 10% lessthan the percentage of non-responders receiving the standard of care; insome embodiments, a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof, results in a duration of illness that is in therange of about 10% to about 30% less than compared to the duration ofillness experienced by a subject who is untreated for the infection; andin some embodiments, a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof, results in a severity of a symptom (such as oneof those described herein) that is 25% less than compared to theseverity of the same symptom experienced by a subject who is untreatedfor the infection. Methods of quantifying the severity of a side effectand/or symptom are known to those skilled in the art.

TABLE 1 Percentage of Percentage of Percentage of Percentage of Numberof Severity of non-responders relapsers resistance viral load reboundside effects side effect(s) 10% less 10% less 10% less 10% less 10% less10% less 25% less 25% less 25% less 25% less 25% less 25% less 40% less40% less 40% less 40% less 40% less 40% less 50% less 50% less 50% less50% less 50% less 50% less 60% less 60% less 60% less 60% less 60% less60% less 70% less 70% less 70% less 70% less 70% less 70% less 80% less80% less 80% less 80% less 80% less 80% less 90% less 90% less 90% less90% less 90% less 90% less about 10% about 10% about 10% about 10% about10% about 10% to about to about to about to about to about to about 30%less 30% less 30% less 30% less 30% less 30% less about 20% about 20%about 20% about 20% about 20% about 20% to about to about to about toabout to about to about 50% less 50% less 50% less 50% less 50% less 50%less about 30% about 30% about 30% about 30% about 30% about 30% toabout to about to about to about to about to about 70% less 70% less 70%less 70% less 70% less 70% less about 20% about 20% about 20% about 20%about 20% about 20% to about to about to about to about to about toabout 80% less 80% less 80% less 80% less 80% less 80% less Duration ofDuration of Duration of Severity of Severity of Severity of illnessillness illness symptom(s) symptom(s) symptom(s) 10% less 60% less about10% 10% less 60% less about 10% to about to about 30% less 30% less 25%less 70% less about 20% 25% less 70% less about 20% to about to about50% less 50% less 40% less 80% less about 30% 40% less 80% less about30% to about to about 70% less 70% less 50% less 90% less about 20% 50%less 90% less about 20% to about to about 80% less 80% less

As discussed above, in some embodiments, a compound of Formula (I), or apharmaceutically acceptable salt thereof, is a panviral nucleosideanalog. Various embodiments provide a panviral treatment that comprisesa compound of Formula (I), or a pharmaceutically acceptable saltthereof. In this context, the term “panviral treatment” refers to acompound of Formula (I), or a pharmaceutically acceptable salt thereof,that is panviral as described above. Such panviral treatments are thuseffective to treat two or more viral infections, where the viruses thatcause the infections are caused by viruses from two or more virusfamilies. For example, in an embodiment, the panviral treatmentcomprises a compound, or a pharmaceutically acceptable salt thereof,that is effective to treat viral infections caused by viruses in two ormore families selected from the group consisting of Picornaviridae,Flaviviridae, Filoviridae, Pneumoviridae and Coronaviridae. Thoseskilled in the art are aware of numerous subfamilies, genera and speciesof viruses and the families in which they are categorized. For example,in an embodiment the panviral treatment comprises a compound, or apharmaceutically acceptable salt thereof, that is effective to treatviral infections selected from a Rhinovirus infection in thePicornaviridae family; a Dengue virus infection or a Hepacivirusinfection in the Flaviviridae family; an Ebolavirus infection in theFiloviridae family; a human respiratory syncytial virus (HRSV) infectionin the Pneumoviridae family; and a human α-coronavirus viral infectionand/or a human β-coronavirus viral infection in the Coronaviridaefamily. In various embodiments, the panviral treatment comprises acompound, or a pharmaceutically acceptable salt thereof, having lowtoxicity as described elsewhere herein. Examples of panviral treatmentsinclude those comprising compounds 1-15 as described in the Examplesbelow, and pharmaceutically acceptable salts thereof.

In some embodiments, the compound can be a compound of Formula (I),wherein the compound of Formula (I) is a mono, di, or triphosphate, or apharmaceutically acceptable salt of any of the foregoing. In still otherembodiments, the compound can be a compound of Formula (I), wherein thecompound of Formula (I) is a thiomonophosphate, alpha-thiodiphosphate,or alpha-thiotriphosphate, or a pharmaceutically acceptable salt of anyof the foregoing. In some embodiments, the compound of Formula (I), or apharmaceutical acceptable salt of any of the foregoing, that can be usedto ameliorate and/or treat a Picornaviridae, Flaviviridae, Filoviridae,Pneumoviridae and/or Coronaviridae viral infection and/or inhibitreplication of a Picornaviridae, Flaviviridae, Filoviridae,Pneumoviridae and/or Coronaviridae virus can be any of the embodimentsdescribed herein.

As used herein, a “subject” refers to an animal that is the object oftreatment, observation or experiment. “Animal” includes cold- andwarm-blooded vertebrates and invertebrates such as fish, shellfish,reptiles and, in particular, mammals. “Mammal” includes, withoutlimitation, mice, rats, rabbits, guinea pigs, dogs, cats, sheep, goats,cows, horses, primates, such as monkeys, chimpanzees, and apes, and, inparticular, humans. In some embodiments, the subject is human.

As used herein, the terms “treating,” “treatment,” “therapeutic,” or“therapy” do not necessarily mean total cure or abolition of the diseaseor condition. Any alleviation of any undesired signs or symptoms of adisease or condition, to any extent can be considered treatment and/ortherapy. Furthermore, treatment may include acts that may worsen thepatient's overall feeling of well-being or appearance.

The terms “therapeutically effective amount” and “effective amount” areused to indicate an amount of an active compound, or pharmaceuticalagent, that elicits the biological or medicinal response indicated. Forexample, an effective amount of compound can be the amount needed toprevent, alleviate or ameliorate symptoms of disease or prolong thesurvival of the subject being treated This response may occur in atissue, system, animal or human and includes alleviation of the signs orsymptoms of the disease being treated. Determination of an effectiveamount is well within the capability of those skilled in the art, inview of the disclosure provided herein. The effective amount of thecompounds disclosed herein required as a dose will depend on the routeof administration, the type of animal, including human, being treated,and the physical characteristics of the specific animal underconsideration. The dose can be tailored to achieve a desired effect, butwill depend on such factors as weight, diet, concurrent medication andother factors which those skilled in the medical arts will recognize.

As will be readily apparent to one skilled in the art, the useful invivo dosage to be administered and the particular mode of administrationwill vary depending upon the age, weight, the severity of theaffliction, and mammalian species treated, the particular compoundsemployed, and the specific use for which these compounds are employed.The determination of effective dosage levels, that is the dosage levelsnecessary to achieve the desired result, can be accomplished by oneskilled in the art using routine methods, for example, human clinicaltrials and in vitro studies.

The dosage may range broadly, depending upon the desired effects and thetherapeutic indication. Alternatively dosages may be based andcalculated upon the surface area of the patient, as understood by thoseof skill in the art. Although the exact dosage will be determined on adrug-by-drug basis, in most cases, some generalizations regarding thedosage can be made. The daily dosage regimen for an adult human patientmay be, for example, an oral dose of between 0.01 mg and 3000 mg of eachactive ingredient, preferably between 1 mg and 700 mg, e.g. 5 to 200 mg.The dosage may be a single one or a series of two or more given in thecourse of one or more days, as is needed by the subject. In someembodiments, the compounds will be administered for a period ofcontinuous therapy, for example for a week or more, or for months oryears. In some embodiments, a compound of Formula (I), or apharmaceutically acceptable salt thereof, can be administered lessfrequently compared to the frequency of administration of an agentwithin the standard of care. In some embodiments, a compound of Formula(I), or a pharmaceutically acceptable salt thereof, can be administeredone time per day. For example, a compound of Formula (I), or apharmaceutically acceptable salt thereof, can be administered one timeper day to a subject suffering from a picornavirus infection. In someembodiments, the total time of the treatment regime with a compound ofFormula (I), or a pharmaceutically acceptable salt thereof, can be lesscompared to the total time of the treatment regime with the standard ofcare.

In instances where human dosages for compounds have been established forat least some condition, those same dosages may be used, or dosages thatare between about 0.1% and 500%, more preferably between about 25% and250% of the established human dosage. Where no human dosage isestablished, as will be the case for newly-discovered pharmaceuticalcompositions, a suitable human dosage can be inferred from ED₅₀ or ID₅₀values, or other appropriate values derived from in vitro or in vivostudies, as qualified by toxicity studies and efficacy studies inanimals.

In cases of administration of a pharmaceutically acceptable salt,dosages may be calculated as the free base. As will be understood bythose of skill in the art, in certain situations it may be necessary toadminister the compounds disclosed herein in amounts that exceed, oreven far exceed, the above-stated, preferred dosage range in order toeffectively and aggressively treat particularly aggressive diseases orinfections.

Dosage amount and interval may be adjusted individually to provideplasma levels of the active moiety which are sufficient to maintain themodulating effects, or minimal effective concentration (MEC). The MECwill vary for each compound but can be estimated from in vitro data.Dosages necessary to achieve the MEC will depend on individualcharacteristics and route of administration. However, HPLC assays orbioassays can be used to determine plasma concentrations. Dosageintervals can also be determined using MEC value. Compositions should beadministered using a regimen which maintains plasma levels above the MECfor 10-90% of the time, preferably between 30-90% and most preferablybetween 50-90%. In cases of local administration or selective uptake,the effective local concentration of the drug may not be related toplasma concentration.

It should be noted that the attending physician would know how to andwhen to terminate, interrupt, or adjust administration due to toxicityor organ dysfunctions. Conversely, the attending physician would alsoknow to adjust treatment to higher levels if the clinical response werenot adequate (precluding toxicity). The magnitude of an administrateddose in the management of the disorder of interest will vary with theseverity of the condition to be treated and to the route ofadministration. The severity of the condition may, for example, beevaluated, in part, by standard prognostic evaluation methods. Further,the dose and perhaps dose frequency, will also vary according to theage, body weight, and response of the individual patient. A programcomparable to that discussed above may be used in veterinary medicine.

Compounds disclosed herein can be evaluated for efficacy and toxicityusing known methods. For example, the toxicology of a particularcompound, or of a subset of the compounds, sharing certain chemicalmoieties, may be established by determining in vitro toxicity towards acell line, such as a mammalian, and preferably human, cell line. Theresults of such studies are often predictive of toxicity in animals,such as mammals, or more specifically, humans. Alternatively, thetoxicity of particular compounds in an animal model, such as mice, rats,rabbits, or monkeys, may be determined using known methods. The efficacyof a particular compound may be established using several recognizedmethods, such as in vitro methods, animal models, or human clinicaltrials. When selecting a model to determine efficacy, the skilledartisan can be guided by the state of the art to choose an appropriatemodel, dose, route of administration and/or regime.

Combination Therapies

In some embodiments, the compounds disclosed herein, such as a compoundof Formula (I), or a pharmaceutically acceptable salt thereof, or apharmaceutical composition that includes a compound described herein, ora pharmaceutically acceptable salt thereof, can be used in combinationwith one or more additional agent(s) for treating, ameliorating and/orinhibiting a Picornaviridae, Flaviviridae, Filoviridae, Pneumoviridaeand/or Coronaviridae viral infection.

In some embodiments, a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof, can be administered with one or more additionalagent(s) together in a single pharmaceutical composition. In someembodiments, a compound of Formula (I), or a pharmaceutically acceptablesalt thereof, can be administered with one or more additional agent(s)as two or more separate pharmaceutical compositions. For example, acompound of Formula (I), or a pharmaceutically acceptable salt thereof,can be administered in one pharmaceutical composition, and at least oneof the additional agents can be administered in a second pharmaceuticalcomposition. If there are at least two additional agents, one or more ofthe additional agents can be in a first pharmaceutical composition thatincludes a compound of Formula (I), or a pharmaceutically acceptablesalt thereof, and at least one of the other additional agent(s) can bein a second pharmaceutical composition.

The dosing amount(s) and dosing schedule(s) when using a compound ofFormula (I), or a pharmaceutically acceptable salt thereof, or apharmaceutical composition that includes a compound of Formula (I), or apharmaceutically acceptable salt thereof, and one or more additionalagents are within the knowledge of those skilled in the art. Forexample, when performing a conventional standard of care therapy usingart-recognized dosing amounts and dosing schedules, a compound ofFormula (I), or a pharmaceutically acceptable salt thereof, or apharmaceutical composition that includes a compound of Formula (I), or apharmaceutically acceptable salt thereof, can be administered inaddition to that therapy, or in place of one of the agents of acombination therapy, using effective amounts and dosing protocols asdescribed herein.

The order of administration of a compound of Formula (I), or apharmaceutically acceptable salt thereof, with one or more additionalagent(s) can vary. In some embodiments, a compound of Formula (I), or apharmaceutically acceptable salt thereof, can be administered prior toall additional agents. In other embodiments, a compound of Formula (I),or a pharmaceutically acceptable salt thereof, can be administered priorto at least one additional agent. In still other embodiments, a compoundof Formula (I), or a pharmaceutically acceptable salt thereof, can beadministered concomitantly with one or more additional agent(s). In yetstill other embodiments, a compound of Formula (I), or apharmaceutically acceptable salt thereof, can be administered subsequentto the administration of at least one additional agent. In someembodiments, a compound of Formula (I), or a pharmaceutically acceptablesalt thereof, can be administered subsequent to the administration ofall additional agents.

In some embodiments, the combination of a compound of Formula (I), or apharmaceutically acceptable salt thereof, in combination with one ormore additional agent(s) can result in an additive effect. In someembodiments, the combination of a compound of Formula (I), or apharmaceutically acceptable salt thereof, used in combination with oneor more additional agent(s) can result in a synergistic effect. In someembodiments, the combination of a compound of Formula (I), or apharmaceutically acceptable salt thereof, used in combination with oneor more additional agent(s) can result in a strongly synergistic effect.In some embodiments, the combination of a compound of Formula (I), or apharmaceutically acceptable salt thereof, in combination with one ormore additional agent(s) is not antagonistic.

As used herein, the term “antagonistic” means that the activity of thecombination of compounds is less compared to the sum of the activitiesof the compounds in combination when the activity of each compound isdetermined individually (i.e. as a single compound). As used herein, theterm “synergistic effect” means that the activity of the combination ofcompounds is greater than the sum of the individual activities of thecompounds in the combination when the activity of each compound isdetermined individually. As used herein, the term “additive effect”means that the activity of the combination of compounds is about equalto the sum of the individual activities of the compound in thecombination when the activity of each compound is determinedindividually.

A potential advantage of utilizing a compound of Formula (I), or apharmaceutically acceptable salt thereof, in combination with one ormore additional agent(s) may be a reduction in the required amount(s) ofone or more additional agent(s) that is effective in treating an a viralinfection, as compared to the amount required to achieve sametherapeutic result when one or more additional agent(s) are administeredwithout a compound of Formula (I), or a pharmaceutically acceptable saltthereof. Another potential advantage of utilizing a compound of Formula(I), or a pharmaceutically acceptable salt thereof, in combination withone or more additional agent(s) is that the use of two or more compoundshaving different mechanism of actions can create a higher barrier to thedevelopment of resistant viral strains compared to the barrier when acompound is administered as monotherapy.

Additional advantages of utilizing a compound of Formula (I), or apharmaceutically acceptable salt thereof, in combination with one ormore additional agent(s) may include little to no cross resistancebetween a compound of Formula (I), or a pharmaceutically acceptable saltthereof, and one or more additional agent(s) thereof; different routesfor elimination of a compound of Formula (I), or a pharmaceuticallyacceptable salt thereof, and one or more additional agent(s); little tono overlapping toxicities between a compound of Formula (I), or apharmaceutically acceptable salt thereof, and one or more additionalagent(s); little to no significant effects on cytochrome P450; little tono pharmacokinetic interactions between a compound of Formula (I), or apharmaceutically acceptable salt thereof, and one or more additionalagent(s); greater percentage of subjects achieving a sustained viralresponse compared to when a compound is administered as monotherapyand/or a decrease in treatment time to achieve a sustained viralresponse compared to when a compound is administered as monotherapy.

-   For treating of a viral infection, examples of additional agents    that can be used in combination with a compound of Formula (I), or a    pharmaceutically acceptable salt thereof, or a pharmaceutical    composition that includes a compound of Formula (I), or a    pharmaceutically acceptable salt thereof, include, but are not    limited to, ribavirin and an interferon (including those described    herein).

EXAMPLES

Additional embodiments are disclosed in further detail in the followingexamples, which are not in any way intended to limit the scope of theclaims.

Compounds

The compounds of Formula (I) illustrated in Tables 1-3 can be preparedin various ways, using techniques known to those skilled in the art asguided by the detailed teachings provided herein. For example, thecompounds of Formula (I) illustrated in Tables 1-3 can be readilyprepared in view of the detailed teachings set forth herein includingExamples 1-15 below as well as the reaction schemes illustrated in FIGS.1-8. Those skilled in the art will understand that a number ofstructures shown in Table 1-3 are stereospecific (or non-stereospecific)and/or are depicted as having unfilled valencies, and that isotopicand/or stereochemical variants, including racemates, diastereomers,enantiomers and/or deuterated versions, can be prepared in accordancewith the guidance provided herein.

TABLE 1 No. Compound Structure 1

2

3

4

TABLE 1A No. Compound Name 1(2R,3R,4S,5S)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-fluoro-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile 2 (2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-azido-3,4-dihydroxy-5-(Hydroxymethyl)tetrahydrofuran-2-carbonitrile 3 (2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-(fluoromethyl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydro-furan-2-carbonitrile 4(2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5- (hydroxymethyl)tetrahydrofuran-2,5-dicarbo- nitrile

TABLE 2 No. Compound Structure 5

6

7

8

9

10

11

12

13

14

TABLE 2A No. Compound Name 5 Isopropyl((((2S,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-D-alaninate 6 Isopropyl((((2S,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate 7 Diisopentyl((((2S,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-aspartate 8 Neopentyl((((2S,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate 9 2-Ethylbutyl((((2S,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-D-alaninate 11 Isopropyl((((2R,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-2-azido-5-cyano-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-D-alaninate 12((2S,3S,4R,5R)-5-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methyl tetrahydrogen triphosphate 13((2R,3S,4R,5R)-5-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-(fluoromethyl)-3,4-dihydroxytetrahydrofuran-2-yl)methyl tetrahydrogentriphosphate 14((2R,3S,4R,5R)-5-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-2-azido-5-cyano-3,4-dihydroxytetrahydrofuran-2-yl)methyl tetrahydrogen triphosphate

TABLE 3 No. Compound Structure 15

TABLE 3A No. Compound Name 15(2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-(chloromethyl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydro-furan-2-carbonitrile

Synthesis

Exemplary compounds useful in methods of the invention will now bedescribed by reference to the illustrative synthetic schemes for theirgeneral preparation below and the specific examples that follow.Artisans will recognize that, to obtain the various compounds herein,starting materials may be suitably selected so that the ultimatelydesired substituents will be carried through the reaction scheme with orwithout protection as appropriate to yield the desired product.Alternatively, it may be necessary or desirable to employ, in the placeof the ultimately desired substituent, a suitable group that may becarried through the reaction scheme and replaced as appropriate with thedesired substituent. Unless otherwise specified, the variables are asdefined above in reference to Formula (I). Reactions may be performedbetween the melting point and the reflux temperature of the solvent, andpreferably between 0° C. and the reflux temperature of the solvent.Reactions may be heated employing conventional heating or microwaveheating. Reactions may also be conducted in sealed pressure vesselsabove the normal reflux temperature of the solvent. Abbreviations andacronyms used herein include those used in Table 4.

TABLE 4 Term Acronym Acetonitrile ACN Aqueous aq Atmosphere atm Broad brDiatomaceous Earth Celite ® 1,8-Diazabicyclo[5.4.0]undec-7-ene DBUDichloromethane DCM Diisopropylethylamine DIPEA, DIEA, or Hunig's base4-Dimethylaminopyridine DMAP N,N-Dimethylformamide DMF DimethylsulfoxideDMSO Diethyl ether Ether, Et₂O Ethyl Acetate EtOAc, or EA Ethanol EtOHNormal-phase silica gel chromatography FCC Grams g Hours h High-pressureliquid chromatography HPLC Hertz Hz Liquid chromatography and massspectrometry LCMS Molar M Mass to charge ratio m/z Methanol MeOHMilligrams mg Minute min Milliliter mL Microliter μL Millimoles mmolMass spectrometry MS Normal N N-Iodosuccinimide NIS Nuclear magneticresonance NMR CF₃SO₃— or triflate OTf Parts per million ppm Retentiontime R_(t) Room temperature rt Saturated sat Temperature T TriethylamineTEA Trifluoroacetic acid TFA Tetrahydrofuran THF Thin layerchromatography TLC Volume in milliliters of solvent per gram of V, orvolumes substrate

Exemplary compounds useful in methods of the invention will now bedescribed by reference to the illustrative synthetic schemes for theirgeneral preparation below and the specific examples to follow.

According to SCHEME 1, fluorination of a compound of formula (V), wherePG is benzyl, is achieved using a fluorinating agent such asdiethylaminosulfur trifluoride (DAST), and the like, in a suitablesolvent such as toluene, DCM, and the like, at temperatures ranging from0 OC to 60° C. A compound of formula (VII), is prepared in two stepsfrom a compound of formula (VI) where PG is benzyl. Acid-catalyzedhydrolysis of the 1,2-acetonide with HCl in a dioxane-methanol mixturefollowed by reaction with NaH and benzyl bromide provides a compound offormula (VII), where PG is benzyl and R^(4A) is CH₂F.

According to SCHEME 2, a compound of formula (VII), where PG is benzyland R^(4A) is H, is prepared from D-ribofuranose in two steps. In afirst step, D-ribofuranose is methylated employing an acid such asH₂SO₄, in MeOH. In a second step, protection with a suitable protectinggroup such as benzyl, employing conditions known to one skilled in theart, provides a compound of formula (VII). Removal of the methyl groupin a compound of formula (VII), where R^(4A) is H is accomplished usingan acid such a TFA, and the like, in water, for a period of 10-15 h, toprovide a compound of formula (VIII), where PG is benzyl. Where R^(4A)is CH₂F, the process of Scheme 2 can be modified as indicated in Scheme2A.

According to SCHEME 3, a compound of formula (VIII) where PG is benzyland R^(4A) is H or CH₂F, is oxidized employing chromium-mediatedoxidation such as PCC, or DMSO/Ac₂O, to provide a ribolactone compoundof formula (IX).

According to SCHEME 4, a compound of formula (X) is prepared in twosteps from a commercially available or synthetically accessible compoundof formula (III), where HAL is Br, and a commercially available orsynthetically accessible compound of formula (IX), where PG is benzyl,and R^(4A) is H or CH₂F. For example, in a first step, a compound offormula (III) such as 7-bromopyrrolo[2,1-f][1,2,4]triazin-4-amine isreacted with a base such as NaH and the like, in a suitable solvent suchas THF, and the like, and 1,2-bis(chlorodimethylsilyl)ethane to providea compound of formula (IV) which was not isolated but used directly inthe next step. In a second step, a compound of formula (IV) is reactedwith a base such as n-BuLi, t-BuLi, and the like, in a suitable solventsuch as THF, Et₂O, and the like, at a temperature of −78° C., followedby the addition of a commercially available or synthetically accessibleribolactone compound of formula (IX) such as(3R,4S,5R)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)dihydrofuran-2(3H)-one,(3R,4R,5R)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)dihydrofuran-2(3H)-one,and the like, to provide a compound of formula (X).

According to SCHEME 5, a cyano compound of formula (XI), where R^(4A) isH and PG is benzyl, is prepared from a compound of formula (X). Forexample, a compound of formula (X) is reacted with TMSCN and TMSOTf in asolvent such as DCM, and the like, at a temperature of about −78° C., toprovide a compound of formula (XI). Removal of the three benzylprotecting groups is achieved with a reagent such as boron trichlorideto provide a compound of formula (XII), where R^(1A) is CN and R^(4A) isH.

According to SCHEME 6, a compound of formula (XII) where R^(4A) is H,R^(1A) is CN, is halogenated employing triphenylphosphine, imidazole andiodine, to provide a compound of formula (XIII). An iodo compound offormula (XIII) undergoes a base promoted elimination to provide anolefin compound of formula (XIV).

According to SCHEME 7, treatment of an olefin compound of formula (XIV),where R^(1A) is CN, is halogenated with N-iodosuccinimide (NIS) andTEA-3HF, in a suitable solvent such as ACN, to provide a fluoro iodocompound of formula (XIII), where R^(1A) is CN, R^(4A) is F.

An azide compound of formula (XIII), where R^(4A) is N₃, is prepared bythe addition of iodine azide to the 4′-double bond of a compound offormula (XIV) in a regio and stereospecific manner. For example, iodineazide (generated in situ from iodine monochloride and sodium azide) isadded to a compound of formula (XIV), where R^(1A) is CN, in a solventsuitable such as DMF, to provide an azide compound of formula (XIII),where R^(4A) is N₃ and R^(1A) is CN.

Protection, employing benzoyl chloride, in a solvent such as pyridine,at temperatures ranging from 0° C. to room temperature, affords acompound of formula (XVI), where R^(1A) is CN, R^(4A) is N₃ or F, and PGis benzoyl.

According to SCHEME 8, a compound of formula (XIII), where R^(1A) is CNand R^(4A) is F, is protected to provide an methoxymethylene compound offormula (XVII). Reaction of a compound of formula (XVII) in anucleophilic substitution reaction with a nucleophile such as potassiumbenzoate, and the like, 18-crown-6, in a suitable solvent such as DMSO,DMF, and the like, at a temperature of about 100° C., provides acompound of formula (XVIII), where PG is benzoyl. Deprotection of thebenzoyl protecting group (PG) with ammonia in methanol provides acompound of formula (XIX), where R^(1A) is CN and R^(4A) is F.

According to SCHEME 9, protection of 2′ and 3′-OH of a compound offormula (XIV), where R^(1A) is CN, with tert-butyl dimethylsilyl groupsis achieved employing tert-butyl(chloro)dimethylsilane, in the presenceof imidazole and DMAP, in a suitable solvent such as DMF, and the like,at a temperature of about 40-60° C. Subsequent benzoyl protection,employing conditions previously described provides a compound of formula(XX), where each PGt is TBDMS, and PG is Bz. Stereoselective epoxidationwith a dioxirane such as dimethyldioxirane (DMDO, generated in situ byadding acetone to an aqueous solution containing potassiumperoxymonosulfate (Oxone)), in a suitable solvent such as DCM, affordsan epoxide compound of formula (XXI). A compound of formula (XXII),where R^(1A) and R^(4A) are CN, and PG² is trimethylsilyl, is preparedby ring opening of the epoxide of a compound of formula (XXI) in thepresence of a Lewis Acid such as InBr₃, TiCl₄, and the like, andcyanotrimethylsilane (TMSCN), in a suitable solvent such as DCM, and thelike.

According to SCHEME 10, a chlorophosphoramidate of formula (XXV), whereZ^(3A) is 0, and R^(9A) is an N-linked amino acid or an optionallysubstituted N-linked amino acid ester derivative, is prepared byreacting phenyl phosphorodichloridate with a commercially available orsynthetically accessible amino acid or an optionally substituted aminoacid ester derivative, a base such as triethylamine (TEA), and the like,in a suitable solvent such as DCM. Employing the Uchiyama procedure(Uchiyama, M.; Aso, Y.; Noyori, R.; Hayakawa, Y. O-selectivephosphorylation of nucleosides without N-protection. J. Org. Chem. 1993,58, 373-379), a chlorophosphoramidate compound of formula (XXV) isreacted with a compound of formula (XIX), where R^(1A) is CN and R^(4A)is F, in the presence of N-methylimidazole, in a suitable solvent suchas ACN. Subsequent deprotection of the tethered oxomethylene isaccomplished employing an acid such as HCl, HCOOH, and the like, in asuitable solvent such as dioxane, water, or a mixture thereof, toprovide a compound of Formula (Ia), where R^(1A) is CN, R^(2A) andR^(3A) are H, and R^(4A) is F.

Compounds of Formula (I) may be converted to their corresponding saltsusing methods known to one of ordinary skill in the art. For example, anamine of Formula (I) is treated with trifluoroacetic acid, HCl, orcitric acid in a solvent such as Et₂O, CH₂Cl₂, THF, MeOH, chloroform, orisopropanol to provide the corresponding salt form. Alternately,trifluoroacetic acid or formic acid salts are obtained as a result ofreverse phase HPLC purification conditions. Crystalline forms ofpharmaceutically acceptable salts of compounds of Formula (I) may beobtained in crystalline form by recrystallization from polar solvents(including mixtures of polar solvents and aqueous mixtures of polarsolvents) or from non-polar solvents (including mixtures of non-polarsolvents).

Where the compounds described herein have at least one chiral center,they may accordingly exist as enantiomers. Where the compounds possesstwo or more chiral centers, they may additionally exist asdiastereomers. It is to be understood that all such isomers and mixturesthereof are encompassed within the scope of the present invention.

Compounds prepared according to the schemes described above may beobtained as single forms, such as single enantiomers, by form-specificsynthesis, or by resolution. Compounds prepared according to the schemesabove may alternately be obtained as mixtures of various forms, such asracemic (1:1) or non-racemic (not 1:1) mixtures. Where racemic andnon-racemic mixtures of enantiomers are obtained, single enantiomers maybe isolated using conventional separation methods known to one ofordinary skill in the art, such as chiral chromatography,recrystallization, diastereomeric salt formation, derivatization intodiastereomeric adducts, biotransformation, or enzymatic transformation.Where regioisomeric or diastereomeric mixtures are obtained, asapplicable, single isomers may be separated using conventional methodssuch as chromatography or crystallization.

The specific examples described below are provided to further illustratethe invention and various preferred embodiments. In obtaining thecompounds described in the examples below and the correspondinganalytical data, the following experimental and analytical protocolswere followed unless otherwise indicated.

Unless otherwise stated, reaction mixtures were magnetically stirred atroom temperature (rt) under a nitrogen atmosphere. Where solutions were“dried,” they were generally dried over a drying agent such as Na₂SO₄ orMgSO₄. Where mixtures, solutions, and extracts were “concentrated”, theywere typically concentrated on a rotary evaporator under reducedpressure. Reactions under microwave irradiation conditions were carriedout in a Biotage Initiator or CEM (Microwave Reactor) Discoverinstrument.

Normal-phase silica gel chromatography (FCC) was performed on silica gel(SiO₂) using prepacked cartridges.

Preparative reverse-phase high performance liquid chromatography (RPHPLC) was performed on an Agilent HPLC with an Xterra Prep RP18 column(5 μM, 30×100 or 50×150 mm) or an XBridge C18 OBD column (5 μM, 30×100or 50×150 mm), and a mobile phase of 5% ACN in 20 mM NH₄OH was held for2 min, then a gradient of 5-99% ACN over 15 min, then held at 99% ACNfor 5 min, with a flow rate of 40 or 80 mL/min.

Mass spectra (MS) were obtained on an Agilent series 1100 MSD usingelectrospray ionization (ESI) in positive mode unless otherwiseindicated. Calculated (calcd.) mass corresponds to the exact mass.

Nuclear magnetic resonance (NMR) spectra were obtained on Bruker 400 MHzmodel DRX spectrometers. Definitions for multiplicity are as follows:s=singlet, d=doublet, t=triplet, q=quartet, m=multiplet, br=broad. Itwill be understood that for compounds comprising an exchangeable proton,said proton may or may not be visible on an NMR spectrum depending onthe choice of solvent used for running the NMR spectrum and theconcentration of the compound in the solution.

Chemical names were generated using ChemDraw Ultra 12.0, ChemDraw Ultra14.0 (CambridgeSoft Corp., Cambridge, Mass.) or ACD/Name Version 10.01(Advanced Chemistry).

Intermediate 1(2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile

Step A. 7-Bromopyrrolo[2,1-f][1,2,4]triazin-4-amine

To a solution of pyrrolo[2,1-f][1,2,4]triazin-4-amine (2.1 g, 15.66mmol, 1.00 equiv) in DMF (20 mL) was added1,3-dibromo-5,5-dimethylimidazolidine-2,4-dione (2.24 g, 7.83 mmol, 0.53equiv) at −20° C. in batches. The resulting solution was stirred for 1 hat −20° C., then quenched by the addition of 30 mL of sat. sodiumsulfite (aq). After filtration, the filter was dissolved in 200 ml ofethyl acetate, washed with 100 mL of sat. sodium carbonate (aq.), driedover sodium sulfate and concentrated under reduced pressure. Thisresulted in 2.50 g (75%) of the title compound as a white solid. MS m/z[M+H]⁺ (ESI): 213, 215.

Step B.(3R,4R,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-bis(benzloxy)-5-((benzyloxy)methyl)tetrahydrofuran-2-ol

To a solution of 7-bromopyrrolo[2,1-f][1,2,4]triazin-4-amine (2 g, 9.39mmol, 2.98 equiv) in anhydrous THF (200 mL) under inert atmosphere, wasadded 1,1,4,4-tetramethyl-1,4-dichlorodisilyethylene(2.2 g, 9.46 mmol,1.1 equiv) along with sodium hydride (754 mg, 18.92 mmol, 2.2 equiv) andthe mixture was stirred for 20 min at room temperature. The reaction wasthen cooled to −78° C. before n-butyllithium (11.4 mL, 28.38 mmol, 2.5 Min hexanes) was added slowly over 10 min. The reaction was allowed tostir for a further 15 min before (3R,4R,5R)-3,4-bis(benzyloxy)-5-[(benzyloxy)methyl]oxolan-2-one (3.6 g, 8.60mmol, 1.00 equiv) (dissolved in 5 mL THF) was added dropwise. Theresulting solution was stirred for 1 h at −78° C., then quenched by theaddition of 200 mL sat. ammonium chloride (aq.). The resulting solutionwas extracted with of ethyl acetate (200 mL×3) and the organic layerscombined, dried over sodium sulfate and concentrated under reducedpressure. The crude product was purified by reverse phase flashchromatography (ACN/H₂O). This resulted in 2 g (42%) of the titlecompound as a yellow solid. MS m/z [M+H]⁺ (ESI):553.

Step C.(3R,4R,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)tetrahydrofuran-2-carbonitrile

To a solution of(3R,4R,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)tetrahydrofuran-2-ol(2.2 g, 3.98 mmol, 1.00 equiv) in DCM (80 mL) under inert atmosphere,was added trimethylsilanecarbonitrile (1.86 mL, 3.50 equiv) dropwise at0° C. The resulting solution was stirred for 10 min. To this was addedtrimethylsilyl trifluoromethanesulfonate (3.26 mL, 4.50 equiv) dropwiseat 0° C. The resulting solution was stirred for 2 h at 0° C. thenquenched by the addition of 200 mL of sat. sodium bicarbonate (aq.). Theresulting solution was extracted with 200 mL of DCM and the organiclayers combined and dried over anhydrous sodium sulfate and concentratedunder reduced pressure. The residue was purified on silica gel columnwith ethyl acetate/petroleum ether (1:10-2:1). This resulted in 1.2 g(54%) of the title compound as a yellow solid. MS m/z [M+H]⁺ (ESI): 562.

Step D.(2R,3R,4S,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile

To a solution of(3R,4R,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)tetrahydrofuran-2-carbonitrile(1 g, 1.78 mmol, 1.00 equiv) in DCM (5 mL) under inert atmosphere, wasadded a solution of boron trichloride (1M in DCM, 8 mL, 3.4 eq) dropwiseat 0° C. The resulting solution was stirred for 1 h at 0° C., thenquenched by the addition of potassium carbonate in methanol. Afterfiltration, the resulting solution was concentrated under reducedpressure. The crude product was purified by reverse phase flashchromatography (ACN/H₂O). This resulted in 207 mg (40%) of the titlecompound as a white solid. MS m/z [M+H]⁺ (ESI): 292. ¹H-NMR (DMSO-d₆): δ7.90 (s, 1H), 7.6-8.0 (br, 2H), 6.88 (d, J=4.4 Hz, 1H), 6.86 (d, J=4.4Hz, 1H), 6.1 (br s, 1H), 5.19 (br s, 1H), 4.91 (br s, 1H), 4.62 (d,J=5.2 Hz, 1H), 4.04 (m, 1H), 3.93 (m, 1H), 3.62 (m, 1H), 3.49 (m, 1H).

Intermediate 2(3R,4S,5R)-3,4-Bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)dihydrofuran-2(3H)-one

Step A.(3aR,5R,6S,6aR)-6-(Benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxole

To a solution of diethylaminosulfur trifluoride (DAST) (16 g, 99.38mmol, 1.99 equiv) in toluene (200 mL) under inert atmosphere, was addeda solution of((3aR,5R,6S,6aR)-6-(benzyloxy)-5-((benzyloxy)methyl)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methanol(20 g, 49.94 mmol, 1.00 equiv) in toluene (100 mL) dropwise withstirring at 0° C. The resulting solution was stirred for 5 h at 60° C.The reaction was quenched by the addition of aq. NaHCO₃(3 L), andextracted with EtOAc (3×200 mL). The organic layers were combined anddried over anhydrous sodium sulfate, filtered and concentrated underreduced pressure. Purification on silica gel column with ethylacetate/petroleum ether (1:20)) afforded 12.5 g (62%) of the titlecompound as yellow oil. MS m/z: 403 [M+H]⁺.

Step B.(3R,4S,5R)-4-(Benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)-2-methoxytetrahydrofuran-3-ol

To a solution of(3aR,5R,6S,6aR)-6-(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxole(10 g, 24.8 mmol, 1.00 equiv) in methanol (100 mL) was added a solutionof hydrogen chloride (4M in 1,4-dioxane, 30 mL) at 0° C. The resultingsolution was stirred for 1 h at 25° C., and concentrated under reducedpressure to provide 9 g (crude) of the title compound as yellow oil,which was used directly in the next step without purification. MS m/z:377 [M+H]⁺.

Step C. (2R,3S,4R)-3,4-Bis(benzyloxy)-2-((benzyloxy)methyl)-2-(fluoromethyl)-5-methoxytetrahydrofuran

To a solution of(3R,4S,5R)-4-(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)-2-methoxytetrahydrofuran-3-ol(20 g, 53.13 mmol, 1.00 equiv) in tetrahydrofuran (400 mL) under inertatmosphere, was added sodium hydride (4.3 g, 179.17 mmol, 2.10 equiv) at0° C. in batches and stirred for 0.5 h. To the resulting solution wasadded benzyl bromide (18 g, 105.88 mmol, 2.00 equiv) and stirred for 4 hat 25° C. The reaction was then quenched by the addition of NH₄C₁ aq.(200 mL), and extracted with EtOAc (2×500 mL). The organic layers werecombined, washed with NaCl aq. (500 mL), dried over anhydrous sodiumsulfate, and concentrated under reduced pressure to afford 15 g (crude)of the title compound as yellow oil, which was used directly in nextstep without purification. MS m/z: 489 [M+H]⁺.

Step D.(3R,4S,5R)-3,4-Bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)tetrahydrofuran-2-ol

A solution of(2R,3S,4R)-3,4-bis(benzyloxy)-2-((benzyloxy)methyl)-2-(fluoromethyl)-5-methoxytetrahydrofuran(11 g, 38.58 mmol, 1.00 equiv) in 90% TFA in water (200 mL) was stirredfor 3 h at 25° C. The resulting mixture was concentrated under reducedpressure. Residue was dissolved in EtOAc and washed with sodium chlorideaq. (500 mL), and dried over anhydrous sodium sulfate. Purification ofthe evaporated residue (silica gel column with ethyl acetate/petroleumether (1/3)) afforded 8.9 g (46%) of the title compound as yellow oil.MS m/z: 475 [M+H]⁺.

Step E.(3R,4S,5R)-3,4-Bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)dihydrofuran-2(3H)-one

To a solution of(3R,4S,5R)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)tetrahydrofuran-2-ol(1 g, 2.21 mmol, 1.00 equiv) in DMSO (20 mL), was added Ac₂O (15 mL).The resulting solution was stirred for 16 h at room temperature. Thereaction was then quenched by the addition aq. Na₂CO₃ (50 mL), andextracted with ethyl acetate (3×50 mL). The organic layers were combinedand dried over anhydrous sodium sulfate, filtered and concentrated underreduced pressure. Purification (silica gel column with ethylacetate/petroleum ether (1:5)) afforded 578 mg (58%) of the titlecompound as yellow oil. MS m/z: 473 [M+H]⁺.

Intermediate 3(3R,4S,5R)-5-(chloromethyl)-3,4-dihydroxy-5-(hydroxymethyl)dihydrofuran-2(3H)-one

The title compound may be prepared in a manner analogous to Intermediate2, Steps A-E, with the modification of replacing DAST with PPh₃, CCl₄,DCE, higher temperature, in Step A.

Example 1 Compound 1:(2R,3R,4S,5S)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-fluoro-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile

Step A.(2R,3R,4S,5S)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-(iodomethyl)tetrahydrofuran-2-carbonitrile

To a solution of(2R,3R,4S,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile(Intermediate 1, 6 g, 20.5 mmol) in tetrahydrofuran (120 mL) under inertatmosphere was added triphenylphosphine (10.8 g, 41.2 mmol, 2.00 equiv)and imidazole (6.99 g, 102.7 mol, 5.00 equiv). A solution of iodine(10.4 g, 41.2 mmol, 2.00 equiv) in tetrahydrofuran (10 mL) was addeddropwise to the reaction mixture with stirring at room temperature. Theresulting solution was stirred for 2 h at 50° C. After concentrationunder reduced pressure, the residue was purified by reverse phasechromatography with ACN/H₂O to afford 6 g (72.6%) of the title compoundas a yellow solid. MS m/z: 402 [M+H]⁺.

Step B.(2R,3R,4S)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-methylenetetrahydrofuran-2-carbonitrile

To a solution of(2R,3R,4S,5S)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-(iodomethyl)tetrahydrofuran-2-carbonitrile(12 g, 29.9 mmol) in acetonitrile (240 mL) was added1,8-diazabicyclo[5.4.0]undec-7-ene (15 g, 59.8 mmol, 2.00 equiv) at roomtemperature. The resulting solution was stirred for 4 h at 60° C. Afterconcentration under reduced pressure, the residue was purified byreverse phase chromatography with ACN/H₂O to afford 7 g (79%) of thetitle compound as a yellow solid. MS m/z: 274 [M+H]⁺.

Step C.(2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-fluoro-3,4-dihydroxy-5-(iodomethyl)tetrahydrofuran-2-carbonitrile

To a solution of(2R,3R,4S)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-methylenetetrahydrofuran-2-carbonitrile(2 g, 7.32 mmol, 1.00 equiv) in tetrahydrofuran (60 mL) under inertatmosphere was added triethylamine trihydrofluoride (2.94 g, 18.3 mmol,2.50 equiv) and N-iodosuccinimide (2.47 g, 10.98 mmol, 1.50 equiv) atroom temperature. The resulting solution was stirred for 2 h. Afterconcentration under reduced pressure, the residue was purified byreverse phase chromatography with ACN/H₂O to afford 1 g (33%) of thetitle compound as a yellow solid. MS m/z: 420 [M+H]⁺.

Step D.(2R,3R,4S,5R)-2-(4-Benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-2-cyano-5-fluoro-5-(iodomethyl)tetrahydrofuran-3,4-diyldibenzoate

To a solution of(2R,3R,4S,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-fluoro-3,4-dihydroxy-5-(iodomethyl)tetrahydrofuran-2-carbonitrile (1.1 g, 2.62 mmol) in pyridine (22 mL)under inert atmosphere was added benzoyl chloride (1.66 g, 11.8 mmol,4.50 equiv) dropwise with stirring at 0° C. The resulting solution wasstirred for 2 h at 0° C., and then quenched by the addition of water(100 mL). The resulting solution was extracted with dichloromethane (100mL×2) and the combined organic extracts dried over anhydrous sodiumsulfate. After filtration, the resulting solution was concentrated underreduced pressure. Purification (silica gel column with ethylacetate/petroleum ether (1:10-1:2)) afforded 1.1 g (58%) of the titlecompound as a yellow solid. MS m/z: 732 [M+H]⁺.

Step E.(2R,3R,4S,5S)-2-(4-benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-((benzoyloxy)methyl)-2-cyano-5-fluorotetrahydrofuran-3,4-diyldibenzoate

To a solution of(2R,3R,4S,5R)-2-(4-benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-2-cyano-5-fluoro-5-(iodomethyl)tetrahydrofuran-3,4-diyldibenzoate (700 mg, 0.96 mmol) in N, N-dimethylformamide (70 mL) wasadded potassium benzoate (767 mg, 4.79 mmol, 5.00 equiv) and 18-Crown-6(507.5 mg, 1.92 mmol, 2.00 equiv). The resulting solution was stirredfor 16 h at 100° C. The resulting solution was diluted with ethylacetate, washed with water and dried over anhydrous sodium sulfate.After filtration, the resulting solution was concentrated under reducedpressure. Purification (silica gel column with ethyl acetate/petroleumether (1:10-1:2)) afforded 350 mg (50%) of the title compound as ayellow solid. MS m/z: 726 [M+H]⁺.

Step F.(2R,3R,4S,5S)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-fluoro-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile

A solution of(2R,3R,4S,5S)-2-(4-benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-((benzoyloxy)methyl)-2-cyano-5-fluorotetrahydrofuran-3,4-diyldibenzoate. (590 mg, 0.58 mmol, 1.00 equiv) in 2 N NH₃/MeOH (20 mL) wasstirred for 20 h at room temperature. The resulting mixture wasconcentrated under reduced pressure. Purification (silica gel columnwith DCM/MeOH (6:1)) afforded 150 mg (60%) of the title compound as awhite solid. MS m/z: 310 [M+H]⁺. ¹H-NMR (CD₃OD): δ 7.89 (s, 1H), 7.01(d, J=4.6 Hz, 1H), 6.90 (d, J=4.6 Hz, 1H), 4.75 (d, J=6.3 Hz, 1H), 4.49(dd, J=20.0, 6.4 Hz, 1H), 3.90-3.71 (m, 2H). ¹⁹F-NMR (CD₃OD): δ−125.07.

Example 2 Compound 2: (2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,l-f][1,2,4]triazin-7-yl)-5-azido-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile

Step A.(2R,3R,4S,5S)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-azido-3,4-dihydroxy-5-(iodomethyl)tetrahydrofuran-2-carbonitrile

To a solution of IC1 (1.19 g, 7.3 mmol, 2.50 equiv) in DMF (4 mL) wasadded NaN₃ (951 mg, 14.6 mmol, 5.00 equiv). After stirring for 30 min at30° C., a solution of(2R,3R,4S)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-methylenetetrahydrofuran-2-carbonitrile(Compound 1, product from Step B, 800 mg, 2.92 mmol, 1.00 equiv) in DMF(8 mL) was added to the stirred solution at room temperature. Theresulting solution was stirred for 1 h at room temperature, and thenquenched by the addition of 8 mL of Na₂S₂O₃ (aq.). The resulting mixturewas concentrated under reduced pressure and purified by reverse-phaseflash chromatography (ACN/H₂O) to afford 0.88 g (60%) of the titlecompound as a light yellow solid. MS m/z: 443 [M+H]⁺.

Step B. (2S,3S,4R,5R)-2-Azido-5-(4-benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-(iodomethyl)tetrahydrofuran-3,4-diyldibenzoate

To a solution of(2R,3R,4S,5S)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-azido-3,4-dihydroxy-5-(iodomethyl)tetrahydrofuran-2-carbonitrile(500 mg, 1.13 mmol) in anhydrous pyridine (6 mL) under inert atmospherewas added benzoyl chloride (715 mg, 5.1 mmol, 4.5 equiv) at 0° C. andthe mixture was stirred for 1.5 h at 0° C. The reaction was quenched bythe addition of MeOH (2 mL), and concentrated under reduced pressure,then dissolved in ethyl acetate (100 mL), washed with aq. NaHCO₃(30 mL),aq. NaCl (30 mL) and the organic layers were dried over sodium sulfate,filtered and concentrated under reduced pressure. Purification (silicagel column with PE/EA=2/1) afforded 597 mg (70%) of the title compoundas a yellow solid. MS m/z: 755 [M+H]⁺.

Step C. (2R,3S,4R,5R)-2-azido-5-(4-benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-((2,2,2-trifluoroacetoxy)methyl)tetrahydrofuran-3,4-diyldibenzoate and (2R,3S,4R,5R)-2-azido-5-(4-benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-(hydroxymethyl)tetrahydrofuran-3,4-diyldibenzoate

To a solution of (2S,3S,4R,5R)-2-azido-5-(4-benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-(iodomethyl)tetrahydrofuran-3,4-diyldibenzoate (500 mg, 0.66 mmol) in 1,2-dichloroethane (10 mL) was addedCF₃COOAg (1.46 g, 6.6 mmol, 10 equiv) at room temperature. The resultingsolution was stirred for 8 h at 90° C. protected from light. Theresulting solution was diluted with ethyl acetate (100 mL), and washedwith aq. NaHCO₃(30 mL), aq. NaCl (30 mL), dried over sodium sulfate,filtered and concentrated under reduced pressure to afford 450 mg ofm(2R,3S,4R,5R)-2-azido-5-(4-benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-((2,2,2-trifluoroacetoxy)methyl)tetrahydrofuran-3,4-diyldibenzoate and(2R,3S,4R,5R)-2-azido-5-(4-benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-(hydroxymethyl)tetrahydrofuran-3,4-diyldibenzoate as a yellow solid. Crude mixture was used directly for thenext step. MS m/z: 741[M+H]⁺ for(2R,3S,4R,5R)-2-azido-5-(4-benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-((2,2,2-trifluoroacetoxy)methyl)tetrahydrofuran-3,4-diyldibenzoate and 645[M+H]⁺ for (2R,3S,4R,5R)-2-azido-5-(4-benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-(hydroxymethyl)tetrahydrofuran-3,4-diyldibenzoate.

Step D.(2R,3R,4S,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-azido-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile

The mixture of (2R,3S,4R,5R)-2-azido-5-(4-benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-((2,2,2-trifluoroacetoxy)methyl)tetrahydrofuran-3,4-diyldibenzoate and(2R,3S,4R,5R)-2-azido-5-(4-benzamidopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-(hydroxymethyl)tetrahydrofuran-3,4-diyldibenzoate (400 mg, 1.78 mmol) was dissolved in 2N NH₃ in methanol (10mL) and stirred for 20 h at room temperature. The resulting solution wasconcentrated under reduced pressure. Purification by RP-HPLC (XBridgePrep C18 OBD Column, 19×150 mm, 5 μm; mobile phase, A: 10 mM NH₄HCO₃ inwater, B: 10 mM NH₄HCO₃ in ACN (5.0% ACN up to 27.0% in 7 min);Detector, UV 254/220 nm) afforded 56.3 mg (34%) of the title compound asa light yellow solid. MS m/z: 333 [M+H]⁺. ¹H NMR (CD₃OD) δ 7.88 (s, 1H),7.03 (d, J=4.6 Hz, 1H), 6.93 (d, J=4.6 Hz, 1H), 5.02 (d, J=5.8 Hz, 1H),4.43 (d, J=5.8 Hz, 1H), 3.82 (d, J=12.2 Hz, 1H), 3.69 (d, J=12.2 Hz,1H).

Example 3 Compound 3:(2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-(fluoromethyl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile

Step A. (3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][r1,2,4]triazin-7-yl)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)tetrahydrofuran-2-ol

To a solution of 7-bromopyrrolo[2,1-f][1,2,4]triazin-4-amine (0.781 g,3.667 mmol, 1.1 equiv) in anhydrous THF (200 mL) under inert atmosphere,was added sodium hydride (60%, 293 mg, 7.33 mmol, 2.2 equiv), thenimmediately added 1,1,4,4-tetramethyl-1,4-dichlorodisilethylene (0.78 g,3.667 mmol, 1.1 equiv). The mixture was stirred for 20 min at roomtemperature. The reaction was then cooled to −78° C. and n-butyllithium(2.5 M in hexanes, 4.4 mL, 11 mmol, 3.3 equiv) was added slowly over 10min. The reaction was allowed to stir for 20 min before(3R,4S,5R)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)dihydrofuran-2(3H)-one(Intermediate 2, 1.5 g, in 5 mL THF, 3.33 mmol, 1.00 equiv) was addeddropwise. The resulting solution was stirred for 1 h at −78° C., andthen quenched by the addition of aq. NH₄C₁ (200 mL). The resultingsolution was extracted with ethyl acetate (200 mL×3) and the organiclayers were combined, dried over anhydrous sodium sulfate, filtered andconcentrated under reduced pressure. The crude product was purified byreverse phase flash chromatography (ACN/H₂O) to afford 1.15 g (59%) ofthe title compound (two isomers, ratio: 1/1) as a yellow solid. MS m/z:585 [M+H]⁺.

Step B.(2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)tetrahydrofuran-2-carbonitrileand(2S,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)tetrahydrofuran-2-carbonitrile

To a solution of(3R,4S,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)tetrahydrofuran-2-ol(1.15 g, 1.97 mmol, 1.00 equiv) in DCM (20 mL) under inert atmosphere,was added trimethylsilanecarbonitrile (682 mg, 6.90 mmol, 3.50 equiv)dropwise at 0° C. The resulting solution was stirred for 10 min. To thissolution was added trimethylsilyl trifluoromethanesulfonate (1.96 g,8.87 mmol, 4.50 equiv) dropwise at 0° C. The resulting solution wasstirred for 2 h at 0° C., and then quenched by the addition of aq.NaHCO₃ (200 mL). The resulting solution was extracted with DCM (2×200mL) and the organic layers were combined and dried over anhydrous sodiumsulfate, filtered and concentrated under reduced pressure. Purificationby reverse phase flash chromatography (ACN/H₂O) afforded 397 mg (35%) of(2R,3R,4S,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)tetrahydrofuran-2-carbonitrileas a yellow solid and 390 mg (35%) of(2S,3R,4S,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)tetrahydrofuran-2-carbonitrileas a yellow solid. MS m/z: 594 [M+H]⁺.

Step C.(2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-(fluoromethyl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile

To a solution of(2R,3R,4S,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)tetrahydrofuran-2-carbonitrile(350 mg, 0.59 mmol, 1.00 equiv) in DCM (1 mL) under inert atmosphere,was added a solution of boron trichloride (1M in DCM, 20 mL) dropwise at−20° C. The resulting solution was stirred for 1 h at −20° C., and thenquenched by the addition of K₂CO₃/MeOH. The pH value of the solution wasadjusted to 7 with TEA. The solids were filtered off and the resultingfiltrate was concentrated under reduced pressure. The crude product (100mg) was purified by RP-HPLC (XBridge Prep C18 OBD Column, 19×150 mm 55μm; Mobile phase, A:10 mM aq. NH₄HCO₃ B: 10 mM NH₄HCO₃ in MeCN; Gradient5 to 27% B; Detector, UV 254/220 nm) to afford 59.3 mg (31.3%) of thetitle compound as a white solid. MS m/z: 324 [M+H]⁺. ¹H-NMR (CD₃OD): δ7.86 (s, 1H), 6.89 (d, J=4.8 Hz, 1H), 6.82 (d, J=4.8 Hz, 1H), 5.09 (d,J=5.6 Hz, 1H), 4.60-4.80 (m, 2H), 4.37 (d, J=5.6 Hz, 1H), 3.20-3.23 (m,2H). ¹⁹F-NMR (CD₃OD): δ−237.30.

Example 4 Compound 4: (2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,l-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2,5-dicarbonitrile

Step A. (2R,3R,4S)-2-(4-Aminopyrrolo[2,1-f][r1,2,4]triazin-7-yl)-3,4-bis((tert-butyldimethylsilyl)oxy)-5-methylenetetrahydrofuran-2-carbonitrile

To a solution of(2R,3R,4S)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-methylenetetrahydrofuran-2-carbonitrile(800 mg, 2.92 mmol) in DMF (8 mL) under inert atmosphere, was addedimidazole (981 mg, 14.7 mmol, 5 equiv), DMAP (356.2 mg, 2.92 mmol,equiv), tert-butyl(chloro)dimethylsilane (TBDMSCl) (2.2 g, 14.7 mmol, 5equiv) and the mixture was stirred for 5 h at 60° C. The reaction wasquenched by the addition of CH₃OH (5 mL), diluted with ethyl acetate(100 mL), washed with aq. NaHCO₃ (30 mL×2), aq. NaCl (30 mL). Thecombined organic layers were dried over sodium sulfate, filtered andconcentrated under reduced pressure. Purification on silica gel columnwith DCM/MeOH (30:1) afforded 1 g (68%) of the title compound as a lightyellow solid. MS m/z [M+H]⁺ (ESI): 502.

Step B.N-(7-((2R,3R,4S)-3,4-Bis((tert-butyldimethylsilyl)oxy)-2-cyano-5-methylenetetrahydrofuran-2-yl)pyrrolo[2,1-f][1,2,4]triazin-4-yl)benzamide

To a solution of(2R,3R,4S)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-bis((tert-butyldimethylsilyl)oxy)-5-methylenetetrahydrofuran-2-carbonitrile(1 g, 2.0 mmol, 1.0 equiv) in anhydrous pyridine (10 mL) under inertatmosphere, was added benzoyl chloride (330 mg, 2.4 mmol, 1.2 equiv) at0° C. and the mixture was stirred for 2 h at 0° C. The reaction wasquenched by the addition of MeOH (2 mL), and the reaction mixture wasconcentrated under reduced pressure. The crude evaporated residue wasdissolved in ethyl acetate (100 mL), washed with aq. NaHCO₃ (30 mL), aq.NaCl (30 mL). The organic layer was dried over sodium sulfate, filteredand concentrated under reduced pressure. Purification on silica gelcolumn with PE/EA (5:1) afforded 700 mg (58%) of the title compound as ayellow solid. MS m/z [M+H]⁺ (ESI): 606.

Step C.N-(7-((5R,6R,7S)-6,7-Bis((tert-butyldimethylsilyl)oxy)-5-cyano-1,4-dioxaspiro[2.4]heptan-5-yl)pyrrolo[2,1-f][1,2,4]triazin-4-yl)benzamide

To a solution ofN-(7-((2R,3R,4S)-3,4-bis((tert-butyldimethylsilyl)oxy)-2-cyano-5-methylenetetrahydrofuran-2-yl)pyrrolo[2,1-f][1,2,4]triazin-4-yl)benzamide(700 mg, 1.16 mmol, 1.00 equiv) in DCM (10 mL), was added NaHCO₃ (1.46g, 17.4 mmol, 15 equiv), H₂O (7 mL) and acetone (4.03 g, 69.6 mmol, 60equiv). The reaction mixture was cooled to 0° C. then a solution ofoxone (2.85 g, 4.64 mmol, 4 equiv) in H₂O (20 mL) was added dropwise at0° C. The resulting solution was stirred for 3 h at 0° C. then dilutedwith ethyl acetate (100 mL) and washed with aq. Na₂S₂O₃ (20 mL) andbrine (30 mL). The organic layer was dried over sodium sulfate, filteredand concentrated under reduced pressure to afford 750 mg of the titlecompound as a yellow solid. The crude compound was used directly for thenext steps without further purification. MS m/z [M+H]⁺ (ESI): 622.

Step D.N-(7-((2R,3R,4S)-3,4-Bis((tert-butyldimethylsilyl)oxy)-2,5-dicyano-5-(((trimethylsilyl)oxy)methyl)tetrahydrofuran-2-yl)pyrrolo[2,1-f][1,2,4]triazin-4-yl)benzamide

To a solution ofN-(7-((5R,6R,7S)-6,7-bis((tert-butyldimethylsilyl)oxy)-5-cyano-1,4-dioxaspiro[2.4]heptan-5-yl)pyrrolo[2,1-f][1,2,4]triazin-4-yl)benzamide(750 mg, 1.20 mmol) in DCM (20 mL), was added TMSCN (831 mg, 8.4 mmol,7.0 eq). To this mixture was added InBr₃ (1.1 g, 3.0 mmol, 2.5 eq) at 0°C. The reaction mixture was stirred for 3 h at 0° C. The reactionmixture was diluted with ethyl acetate (100 mL), washed with aq. NaHCO₃(30 mL×2), then brine (30 mL). The organic layer was dried over sodiumsulfate, filtered and concentrated under reduced pressure to afford 800mg of crude title compound (two isomers, ratio 3/1) as a yellow solidwhich was used directly for the next steps. MS m/z [M+H]⁺ (ESI): 721.

Step E. N-(7-((2R,3R,4S)-2,5-Dicyano-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)pyrrolo[2,1-f][1,2,4]triazin-4-yl)benzamide

To a solution ofN-(7-((2R,3R,4S)-3,4-bis((tert-butyldimethylsilyl)oxy)-2,5-dicyano-5-(((trimethylsilyl)oxy)methyl)tetrahydrofuran-2-yl)pyrrolo[2,1-f][1,2,4]triazin-4-yl)benzamide(800 mg, 1.11 mmol, 1.00 equiv) in DCM (8 mL), was added TEA 3HF (2.14g, 13.3 mmol, 12 equiv) and TEA (2.69 g, 26.6 mmol, 24 equiv). Theresulting solution was stirred for 20 h at room temperature. Thereaction mixture was concentrated under reduced pressure and the residuedissolved in ethyl acetate (100 mL) and washed with aq. NaHCO₃ (30mL×2), and brine (30 mL). The organic layer was dried over sodiumsulfate, filtered and concentrated under reduced pressure to afford 450mg of crude title compound (two isomers, ratio 3/1) as a red oil. MS m/z[M+H]⁺ (ESI): 421.

Step F.(2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2,5-dicarbonitrileand(2R,3R,4S,5S)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2,5-dicarbonitrile

A solution ofN-(7-((2R,3R,4S)-2,5-dicyano-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)pyrrolo[2,1-f][1,2,4]triazin-4-yl)benzamide(450 mg, 1.07 mmol) in in methanolic ammonia (2N, 14 mL) was stirred for20 h at room temperature. The resulting solution was concentrated underreduced pressure. Purification by RP-HPLC (XBridge Prep C18 OBD Column,19×150 mm 5 um; mobile phase, A: 10 mM aq., NH₄HCO₃, B: 10 mM NH₄HCO₃ inACN; gradient 5% to 27% B in 7 min; detector, UV 254/220 nm) afforded 60mg (16% for four steps) of(2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2,5-dicarbonitrile(Compound 4) as a light yellow solid. MS: m/z 317 [M+H]⁺. ¹H NMR (CD₃OD)δ 7.91 (s, 1H), 6.98 (d, J=4.6 Hz, 1H), 6.94 (d, J=4.6 Hz, 1H), 5.39 (d,J=4.6 Hz, 1H), 4.68 (d, J=4.6 Hz, 1H), 4.05 (s, 2H).

Example 5 Compound 5: Isopropyl((((2S,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-D-alaninate

Step A.(3aR,4R,6R,6aS)-4-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-fluoro-6-(iodomethyl)-2-methoxytetrahydrofuro[3,4-d][1,3]dioxole-4-carbonitrile

To a solution of(2R,3R,4S,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-fluoro-3,4-dihydroxy-5-(iodomethyl)tetrahydrofuran-2-carbonitrile(Compound 1, product from Step C, 500 mg, 1.19 mmol) in dioxane (10 mL)under inert atmosphere was added trimethoxymethane (10 mL), and PTSA(158.2 mg, 0.92 mmol, 0.77 equiv). The resulting solution was stirredfor 3 h at 50° C. The reaction was then quenched by the addition oftriethylamine, and concentrated under reduced pressure. Purification onsilica gel column with DCM/MeOH (100:1-20:1) afforded 340 mg (62%) ofthe title compound as a yellow oil. MS m/z [M+H]⁺ (ESI): 462.

Step B.((3aS,4S,6R,6aR)-6-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-cyano-4-fluoro-2-methoxytetrahydrofuro[3,4-d][1,3]dioxol-4-yl)methylbenzoate

To a solution of(3aR,4R,6R,6aS)-4-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-fluoro-6-(iodomethyl)-2-methoxytetrahydrofuro[3,4-d][1,3]dioxole-4-carbonitrile(1.0 g, 2.2 mmol) in DMF (100 mL) under inert atmosphere was added BzOK(1.74 g, 11 mmol, 5.00 equiv), and 18-Crown-6 (1.15 g, 4.4 mmol, 2.00equiv). The resulting solution was stirred for 16 h at 100° C. Theresulting solution was diluted with of EtOAc, washed with H₂O and driedover anhydrous sodium sulfate, filtered, and then concentrated underreduced pressure. Purification on silica gel column with EA/PE(1:10-3:1) afforded 600 mg (61%) of the title compound as a yellowsolid. MS m/z [M+H]⁺ (ESI): 456.

Step C.(3aR4R,6S,6aS)-4-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-fluoro-6-(hydroxymethyl)-2-methoxytetrahydrofuro[3,4-d][1,3]dioxole-4-carbonitrile

A solution of((3aS,4S,6R,6aR)-6-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-cyano-4-fluoro-2-methoxytetrahydrofuro[3,4-d][1,3]dioxol-4-yl)methylbenzoate (170 mg, 0.37 mmol) in 2N methanolic ammonia (2N, 10 mL) wasstirred for 20 h at room temperature. The resulting solution wasconcentrated under reduced pressure. Purification on silica gel columnwith DCM/MeOH (100:1-20:1) afforded 72 mg (55%) of the title compound asa white solid. MS m/z [M+H]⁺ (ESI): 352.

Step D. Isopropyl((((3aS,4S,6R,6aR)-6-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-cyano-4-fluoro-2-methoxytetrahydrofuro[3,4-d][1,3]dioxol-4-yl)methoxy)(phenoxy)phosphoryl)-D-alaninate

To a solution of(3aR,4R,6S,6aS)-4-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-fluoro-6-(hydroxymethyl)-2-methoxytetrahydrofuro[3,4-d][1,3]dioxole-4-carbonitrile(25 mg, 0.07 mmol) in ACN (1 mL) under inert atmosphere was added1-methyl-1H-imidazole (58.4 mg, 0.71 mmol, 10.00 equiv). Isopropyl(chloro(phenoxy)phosphoryl)-D-alaninate (39.1 mg, 0.13 mmol, 1.80 equiv)(prepared according to McGuigan et al. J. Med. Chem. 2005, 48(10),3504-3515) in ACN (0.4 mL) was added to the reaction mixture dropwisewith stirring at 0° C. The resulting solution was stirred for 1 h atroom temperature. Reaction mixture was diluted with EtOAc, washed withH₂O and dried over anhydrous sodium sulfate, filtered, and thenconcentrated under reduced pressure. Purification on silica gel columnwith DCM/MeOH (10:1)) afforded 25 mg (57%) of the title compound as ayellow oil. MS m/z [M+H]⁺ (ESI): 621.

Step E. Isopropyl ((((2S,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-D-alaninate

A solution of isopropyl((((3aS,4S,6R,6aR)-6-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-cyano-4-fluoro-2-methoxytetrahydrofuro[3,4-d][1,3]dioxol-4-yl)methoxy)(phenoxy)phosphoryl)-D-alaninate(69 mg, 0.11 mmol) in 80% aq. HCOOH (2 mL) was stirred for 16 h at roomtemperature. The resulting mixture was concentrated under reducedpressure. The crude product (70 mg) was purified by RP-HPLC (XBridgeShield RP18 OBD Column, 5 um, 19×150 mm; mobile phase, A; 0.1% aq.HCOOH, B: 0.1% HCOOH in can; gradient 19% to 44% B in 9 min; detector,UV 254 nm) to afford 24 mg (37%) of the title compound as a white solid.MS: m/z 579 [M+H]⁺. ¹H-NMR (CD₃OD): δ 7.80 (d, J=7.2 Hz, 1H), 7.29-7.23(m, 2H), 7.15-7.11 (m, 3H), 6.89-6.82 (m, 2H), 4.94-4.89 (m, 1H),4.77-4.71 (m, 1H), 4.56-4.44 (m, 1H), 4.37-4.27 (m, 2H), 3.85-3.81 (m,1H), 1.25-1.14 (m, 9H). ¹⁹F-NMR (CD₃OD): δ−123.67, −123.88. ³¹P-NMR(CD₃OD): δ 3.43, 3.17.

Example 6 Compound 6: Isopropyl ((((2S,3 S,4R,5R)-5-(4-aminopyrrolo[2,l-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate

Step A. Isopropyl((((3aS,4S,6R,6aR)-6-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-cyano-4-fluoro-2-methoxytetrahydrofuro[3,4-d][1,3]dioxol-4-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate

To a solution of(3aR,4R,6S,6aS)-4-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-fluoro-6-(hydroxymethyl)-2-methoxytetrahydrofuro[3,4-d][1,3]dioxole-4-carbonitrile(Compound 5, product from Step C) (29 mg, 0.08 mmol) in ACN (1.16 mL)under inert atmosphere was added 1-methyl-1H-imidazole (67.7 mg, 0.82mmol, 10.00 equiv). This was followed by the addition of a solution ofisopropyl (chloro(phenoxy)phosphoryl)-L-alaninate (45.36 mg, 0.15 mmol,1.80 equiv) (prepared according to McGuigan et al. J. Med. Chem. 2005,48(10), 3504-3515) in ACN (0.5 mL) dropwise with stirring at 0° C. Theresulting solution was stirred for 1 h at room temperature. Reactionmixture was diluted with EtOAc, washed with H₂O and dried over anhydroussodium sulfate, filtered, and then concentrated under reduced pressure.Purification on silica gel column with DCM/MeOH (10:1) afforded 29 mg(57%) of the title compound as a yellow oil. MS m/z [M+H]⁺ (ESI): 621.

Step B. Isopropyl ((((2S,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate

A solution of isopropyl((((3aS,4S,6R,6aR)-6-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-cyano-4-fluoro-2-methoxytetrahydrofuro[3,4-d][1,3]dioxol-4-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate(80 mg, 0.13 mmol) in 80% aq. HCOOH (8 mL) was stirred for 16 h at roomtemperature. The resulting mixture was concentrated under reducedpressure. The crude evaporated residue was purified by RP-HPLC (XBridgeShield RP18 OBD Column, 5 um, 19×150 mm; mobile phase, A: 0.1% aq.HCOOH, B: 0.1% HCOOH in ACN; gradient 19% to 44% B in 9 min; detector,UV 254 nm) to afford 31.8 mg (43%) of the title compound as a whitesolid. MS: m/z 579 [M+H]⁺. ¹H-NMR (CD₃OD): δ 7.80 (d, J=4.6 Hz, 1H),7.29-7.24 (m, 2H), 7.16-7.10 (m, 3H), 6.93-6.83 (m, 2H), 4.92-4.85 (m,1H), 4.75 (d, J=6.5 Hz, 1H), 4.55-4.46 (m, 1H), 4.34-4.29 (m, 2H),3.87-3.70 (m, 1H), 1.27-1.13 (m, 9H). ¹⁹F-NMR (CD₃OD): δ−123.83,−124.03. ³¹P-NMR (CD₃OD): δ 3.45, 3.29.

Example 7 Compound 7: Diisopentyl((((2S,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihdroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-aspartate

Step A. Diisopentyl L-aspartate hydrochloride

To a solution of L-aspartic acid (1 g, 7.51 mmol) in 3-methylbutan-1-ol(40 mL) was added chlorotrimethylsilane (5.72 mL, 6.00 equiv) dropwisewith stirring at 0° C. The resulting solution was stirred for 48 h atrt. The reaction mixture was concentrated under reduced pressure, theresidue was purified on silica gel column with dichloromethane/methanol(50:1-10:1) to afford 2.1 g (91%) of the title compound as a yellow oil.MS m/z [M+H]⁺ (ESI): 274.

Step B. Diisopentyl (chloro(phenoxy)phosphoryl)-L-aspartate

To a solution of phenoxyphosphonoyl dichloride (340 mg, 1.61 mmol) indichloromethane (8 mL) was added diisopentyl L-aspartate hydrochloride(521 mg, 1.69 mmol, 1.05 equiv), followed by the addition of TEA (0.47mL, 3.38 mmol, 2.10 equiv) dropwise with stirring at −78° C. Theresulting solution was stirred for 3 h at −78° C. to rt. Reactionmixture was diluted with dry cyclohexane, filtered and concentratedunder reduced pressure. Purification on silica gel column with hexane:EA(10:1) afforded 340 mg (47%) of the title compound as a yellow oil.³¹P-NMR (CDCl₃): δ 8.39, 8.29.

Step C. Diisopentyl((((3aS,4S,6R,6aR)-6-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-cyano-4-fluoro-2-methoxytetrahydrofuro[3,4-d][1,3]dioxol-4-yl)methoxy)(phenoxy)phosphoryl)-L-aspartate

To a solution of(3aR,4R,6S,6aS)-4-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-fluoro-6-(hydroxymethyl)-2-methoxytetrahydrofuro[3,4-d][1,3]dioxole-4-carbonitrile(Compound 5, product from Step C, 25 mg, 0.07 mmol) in ACN (1 mL) wasadded Me-Im (58.4 mg, 0.71 mmol, 10.00 equiv), followed by the additionof a solution of diisopentyl (chloro(phenoxy)phosphoryl)-L-aspartate(57.4 mg, 0.13 mmol, 1.80 equiv) in ACN (0.4 mL) dropwise with stirringat 0° C. The resulting solution was stirred for 1 h at room temperature.The resulting solution was diluted with EtOAc, washed with H₂O and theorganic layers dried over anhydrous sodium sulfate, filtered, andconcentrated under reduced pressure. Purification on silica gel columnwith dichloromethane/methanol (10:1) afforded 27 mg (50%) of the titlecompound as a yellow oil. MS m/z [M+H]⁺ (ESI): 763.

Step D. Diisopentyl ((((2S,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-aspartate

A solution of diisopentyl((((3aS,4S,6R,6aR)-6-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-cyano-4-fluoro-2-methoxytetrahydrofuro[3,4-d][1,3]dioxol-4-yl)methoxy)(phenoxy)phosphoryl)-L-aspartate(85 mg, 0.11 mmol, 1.00 equiv) in 80% aq. HCOOH (10 mL) was stirred for16 h at room temperature. The resulting mixture was concentrated underreduced pressure. The crude product (85 mg) was purified by RP-HPLC(XBridge Shield RP18 OBD Column, 5 um, 19×150 mm; mobile phase, A: 0.1%aq. HCOOH, B: 0.1% HCOOH in ACN; gradient 15% to 46% B in 10 min;detector, UV 254 nm) to afford 37.4 mg (47%) of the title compound as awhite solid. MS: m/z 721 [M+H]⁺. ¹H-NMR (CD₃OD): δ 7.88 (d, J=7.0 Hz,1H), 7.43-7.27 (m, 2H), 7.20 (m, 3H), 7.06-6.83 (m, 2H), 4.79 (d, J=6.4Hz, 1H), 4.61-4.31 (m, 3H), 4.26 (m, 1H), 4.22-3.79 (m, 4H), 2.89-2.54(m, 2H), 1.74-1.56 (m 2H), 1.56-1.28 (m, 4H), 0.91 (m, 12H). ¹⁹F-NMR(CD₃OD): δ−123.52, −123.78. ³¹P-NMR (CD₃OD): δ 3.29, 3.07.

Example 8 Compound 8: Neopentyl((((2S,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate

A mixture of(2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2,5-dicarbonitrile(Compound 4, 11 mg, 0.04 mmol), neopentyl(chloro(phenoxy)phosphoryl)-L-alaninate (prepared according to PCTPublication WO 2012/12776 A1) (40 mg, 0.12 mmol) and N-methylimidazole(NMI) (40 μL, 0.48 mmol) in anhydrous acetonitrile (0.4 mL) was stirredovernight under Ar at r.t. then concentrated and purified by RP-HPLC(5-95% B; A: 0.1% aq. HCOOH, B: 0.1% HCOOH in MeCN) to yield 3.2 mg(13%) of the title compound. MS m/z: 607.1 [M+1]⁺. ³¹P-NMR (CD₃CN, D₂O):δ 2.89 (s), 19F-NMR (CD₃CN, D₂O): δ−122.63, −123.0 (2 m).

Example 9 Compound 9: 2-Ethylbutyl((((2S,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-D-alaninate

Step A. 2-Ethylbutyl((((3aS,4S,6R,6aR)-6-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-cyano-4-fluoro-2-methoxytetrahydrofuro[3,4-d][1,3]dioxol-4-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate

A mixture of(3aR,4R,6S,6aS)-4-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-fluoro-6-(hydroxymethyl)-2-methoxytetrahydrofuro[3,4-d][1,3]dioxole-4-carbonitrile(Compound 5, product from Step C, 14 mg, 0.04 mmol), NMI (40 μL, 0.48mmol) and 2-ethylbutyl (chloro(phenoxy)phosphoryl)-L-alaninate (43 mg,0.12 mmol) in acetonitrile (0.5 mL) was stirred at r. t. overnight underAr. The mixture was then diluted with EtOAc and washed consecutivelywith 1N citric acid, water, sat. aq. NaHCO₃, brine and dried (Na₂SO₄).Crude evaporated residue was purified by flash chromatography on silicagel with a gradient of 4-10% MeOH in DCM to yield the title compound asa colorless crisp foam (20 mg, 76%). MS m/z: 663.1 [M+1]⁺.

Step B: 2-Ethylbutyl((((2S,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate

A solution of 2-ethylbutyl((((3aS,4S,6R,6aR)-6-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-cyano-4-fluoro-2-methoxytetrahydrofuro[3,4-d][1,3]dioxol-4-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate(20 mg, 0.03 mmol) in 80% aq. formic acid (1 mL) was stirred for 4 h atr. t., then concentrated and several times co-evaporated with a mixtureof toluene and MeCN, and finally with MeOH containing 1 drop of Et₃N.Crude evaporated residue was purified by flash chromatography on silicagel with a gradient of 4-10% MeOH in DCM to yield 14 mg (77%) of thetitle compound. MS m/z: 618.9 [M−1]⁻. ³¹P-NMR (CD₃OD): δ 3.34, 3.20(2s), ¹⁹F-NMR (CD₃CN, D₂O): δ−124.03, −123.80 (2 m).

Example 10 Compound 10

Step A. propyl L-alaninate hydrochloride

To a solution of L-alanine (500 mg, 5.61 mmol) in propan-1-ol (20 mL)was added thionyl chloride (4 g, 33.62 mmol, 6.00 equiv) dropwise withstirring at 0° C. The resulting solution was stirred for 3 h at 90° C.,and concentrated under reduced pressure. The resulting solution wasdiluted with n-hexane. The solids were collected by filtration. Thisresulted in 900 mg (95%) of propyl L-alaninate hydrochloride as a whitesolid. MS m/z [M+H]⁺ (ESI): 132.

Step B. dipropyl2,2′-((chlorophosphoryl)bis(azanediyl))(2S,2'S)-dipropionate

To a solution of propyl L-alaninate hydrochloride (855 mg, 6.52 mmol,2.00 equiv) in dichloromethane (20 mL) under inert atmosphere was addedPOCl₃ (500 mg, 3.26 mmol, 1.00 equiv) at room temperature. This wasfollowed by the addition of TEA (2.73 mL, 19.56 mmol, 6.00 equiv)dropwise with stirring at −70° C. The resulting solution was stirred for3 h from −70° C. to room temperature. The resulting solution was dilutedwith dry cyclohexane. The solids were filtered out and then concentratedunder reduced pressure. The residue was purified on a silica gel columnwith hexane: EA (10:1-2:1). This resulted in 400 mg (36%) of dipropyl2,2′-((chlorophosphoryl)bis(azanediyl))(2S,2'S)-dipropionate as yellowoil. ³¹P-NMR (CDCl₃, 400 MHz): δ 16.2.

Step C

To a solution of(3aR,4R,6S,6aS)-4-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-6-fluoro-6-(hydroxymethyl)-2-methoxytetrahydrofuro[3,4-d][1,3]dioxole-4-carbonitrile(product from Step C of Example 5) (27 mg, 0.08 mmol) in THF (1.5 mL)under inert atmosphere was added t-BuMgCl (1 M in THF, 0.23 mL, 3.00equiv) dropwise with stirring at −78° C. The resulting solution wasstirred for 30 min at room temperature. To this was added a solution ofdipropyl 2,2′-((chlorophosphoryl)bis(azanediyl))(2S,2'S)-dipropionate(131.8 mg, 0.38 mmol, 5.00 equiv) in tetrahydrofuran (0.2 mL) dropwisewith stirring at −78° C. The resulting solution was stirred for 1 h atroom temperature. The reaction was then quenched with aq. NH₄Cl (50 ml),extracted with ethyl acetate (50 ml×2) and combined organic extractsdried over anhydrous sodium sulfate, filtered and concentrated underreduced pressure. The residue was purified on a silica gel column withdichloromethane/methanol (10:1). This resulted in 26 mg (51%) ofcompound 10A as yellow oil. MS m/z [M+H]⁺ (ESI): 658. Compound 10A hasthe following structure:

Compound 10 was prepared as follows: A solution of Compound 10A (110 mg,0.17 mmol, 1.00 equiv) in 80% HCOOH/H₂O (8 mL) was stirred for 15 h atroom temperature. The resulting mixture was concentrated under reducedpressure. The crude product was purified by RP-HPLC (XBridge Prep OBDC18 Column, 19×250 mm, 5 um; mobile phase, A: 0.1% aq. HCOOH, B: 0.1%HCOOH in ACN; gradient 27% to 42.% B in 8 min; detector, UV 220 nm).This resulted in 31.7 mg (31%) of Compound 10 as a light yellow solid.MS m/z [M+H]⁺ (ESI): 616. ¹H-NMR (CD₃OD): δ 7.93 (s, 1H), 7.01 (d, J=4.6Hz, 1H), 6.93 (d, J=4.6 Hz, 1H), 4.83 (d, J=6.6 Hz, 1H), 4.61 (dd,J=20.3, 6.6 Hz, 1H), 4.34-4.17 (m, 2H), 4.13-3.97 (m, 4H), 3.94-3.80 (m,2H), 1.75-1.59 (m, 4H), 1.33-1.27 (m, 6H), 0.95-0.89 (m, 6H). ¹⁹F-NMR(CD₃OD): δ−124.38 ³¹P-NMR (CD₃OD): δ 13.675.

Example 11 Compound 11: Isopropyl ((((2R,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-2-azido-5-cyano-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-D-alaninate

A mixture of nucleoside(2R,3R,4S,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-azido-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile(Compound 2, 10 mg, 0.03 mmol), NMI (30 μL, 0.36 mmol) and isopropyl(chloro(phenoxy)phosphoryl)-L-alaninate (28 mg, 0.1 mmol) inacetonitrile (0.4 mL) was stirred at r. t. under Ar for 1 h. The mixturewas concentrated and residue partitioned between CH₂Cl₂ and 1N citricacid. Organic layer was washed with water, sat. aq. NaHCO₃, and brine.Combined aqueous washings were reextracted with CH₂Cl₂. Combined organicextracts were dried (Na₂SO₄), evaporated and purified by flashchromatography on silica gel with a gradient of 3-12% MeOH in DCM toyield 4 mg (22%) of the title compound. MS m/z: 602.1 [M+1]+⁻. ³¹P-NMR(CD₃OD): δ 3.21, 3.18 (2s).

Example 12 Compound 12:((2S,3S,4R,5R)-5-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-fluoro-3,4-dihydroxytetrahydrofuran-2-yl)methyltetrahydrogen triphosphate

Dry(2R,3R,4S,5S)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-fluoro-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile(Compound 1, 0.05 mmol) was dissolved in dry PO(OMe)₃ (0.7 mL).N-methylimidazole (0.009 mL, 0.11 mmol) was added followed by POCl₃(0.009 mL, 0.11 mmol), and the mixture was kept at rt for 20-40 mins.The reaction was controlled by LCMS and monitored by the appearance ofcorresponding nucleoside 5′-monophosphate. After completion of thereaction, tetrabutylammonium salt of pyrophosphate (150 mg) was added,followed by DMF (0.5 mL) to get a homogeneous solution. After 1.5 hoursat ambient temperature, the reaction was diluted with water (10 mL) andloaded on the column HiLoad 16/10 with Q Sepharose High Performance.Separation was done in a linear gradient of NaCl from 0 to 1N in 50 mMTRIS-buffer (pH 7.5). Triphosphate was eluted at 75-80% B. Correspondingfractions were concentrated. Desalting was achieved by RP HPLC onSynergy 4 micron Hydro-RP column (Phenominex). A linear gradient ofmethanol from 0 to 30% in 50 mM triethylammonium acetate buffer (pH 7.5)was used for elution. The corresponding fractions were combined,concentrated and lyophilized 3 times to remove excess of buffer toprovide the title compound (see Table 5).

Example 13 Compound 13:((2R3S,4R,5R)-5-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-2-(fluoromethyl)-3,4-dihydroxytetrahydrofuran-2-yl)methyltetrahydrogen triphosphate

The title compound was prepared in the manner described in Example 12using(2R,3R,4S,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-(fluoromethyl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile(Compound 3) as a starting material (see Table 5).

Example 14 Compound 14:((2R3S,4R,5R)-5-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-2-azido-5-cyano-3,4-dihydroxytetrahydrofuran-2-yl)methyltetrahydrogen triphosphate

The title compound was prepared in the manner described in Example 12using(2R,3R,4S,5R)-2-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-azido-3,4-dihydroxy-5-(Hydroxymethyl)tetrahydrofuran-2-carbonitrile(Compound 2) as a starting material (see Table 5).

Example 15 Compound 15:(2R,3R,4S,5R)-2-(4-Aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-(chloromethyl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbonitrile

The title compound may be prepared in a manner analogous to Compound 3,using(3R,4S,5R)-5-(chloromethyl)-3,4-dihydroxy-5-(hydroxymethyl)dihydrofuran-2(3H)-one instead of(3R,4S,5R)-3,4-bis(benzyloxy)-5-((benzyloxy)methyl)-5-(fluoromethyl)dihydrofuran-2(3H)-one(Intermediate 2) in Step A.

TABLE 5 Compound MS (M−1) P(γ) P(β) P(α) 12 548.3 −10.91 (d) −22.27(t)−12.22 (d) 13 561.8 −10.98 (d) −23.43(t) −11.96 (d) 14 571.2 −11.00 (d)−22.40(t) −12.45 (d)

Example A Dengue Antiviral Assay (DENV)

The Dengue virus type 2 strain New Guniea C (NG-C) and the Dengue virustype 4 strain H241 were purchased from ATCC (Manassas, Va.; item numbersVR-1584 and VR-1490, respectively). 24 hours prior to dosing, Huh-7.5cells were plated in 96 well plates at a density of 1.5×10⁵/ml in DMEMmedium supplemented with 10% fetal bovine serum, 1% HEPES buffer, 1%Penicillin/Streptomycin and 1% non-essential amino acids (all Mediatech,Manassas, Va.). At the day of infection, serially diluted compounds wereadded to cells and incubated for 4 hours. After the end of the 4 hourpre-incubation period, cells were infected with either Dengue virus type2 NG-C or Dengue virus type 4 H241. The virus inoculum was selected tocause 80-90% cytopathic effect in five to six days. Infected cells wereincubated for five (NG-C) to six (H241) days at 37° C., 5% CO₂. Todevelop the assay, 100 μl media was replaced with 100 μl CellTiter-Glo®reagent (Promega, Madison, Wis.), and incubated for 10 min at roomtemperature. Luminescence was measured on a Victor X3 multi-label platereader. Potential compound cytotoxicity was determined using uninfectedparallel cultures. Compounds of Formula (I) showed activity in this DENVassay as indicated by the EC₅₀ values provided in Table 6. Compounds ofFormula (I) also showed relatively low values of toxicity in the assayas indicated by the CC₅₀ values provided in Table 6.

Example B

Rhinovirus antiviral assay (HRV1B)

HeLa-OHIO cells (Sigma-Aldrich, St. Louis, Mo.) were plated in 96 wellplates at a density of 1.5×10⁵ cells per well in assay media (MEMwithout phenol red or L-glutamine, supplemented with 1% FBS, 1%penicillin/streptomycin, 2 mM GlutaGro, and 1×MEM nonessential aminoacids, all from Cellgro, Manassas, Va.). Assay setup took place afterallowing cells to adhere for 24 h. Compounds dissolved in DMSO wereserially diluted in assay media to 2× final concentration. Media wasaspirated from the cells, and 100 μl media with compound was added intriplicate. Human rhinovirus 1B (ATCC, Manassas, Va.) was diluted inassay media, and 100 μL was added to cells and compound. The virusinoculum was selected to cause 80-90% cytopathic effect in 4 d. Infectedcells were incubated for 4 d at 33° C., 5% CO₂. To develop the assay,100 μL media was replaced with 100 μL CellTiter-Glo® reagent (Promega,Madison, Wis.), and incubated for 10 mins at RT. Luminescence wasmeasured on a Victor X3 multi-label plate reader. Compounds of Formula(I) showed activity in this HRV1B assay as indicated by the EC₅₀ valuesprovided in Table 6. Compounds of Formula (I) also showed relatively lowvalues of toxicity in the assay as indicated by the CC₅₀ values providedin Table 6.

Example C RSV Antiviral Assay (RSV)

The HeLa-derived cells containing the stable RSV replicon were culturedin DMEM containing 4500 mg/L D-glucose, L-glutamine, and 110 mg/L sodiumpyruvate. The medium was further supplemented with 10% (v/v) FBS(Mediatech), 1% (v/v) penicillin/streptomycin (Mediatech), and 10 μg/mLof Blasticidin (BSD) (Invivogen). Cells were maintained at 37° C. in ahumidified 5% CO₂ atmosphere. On the first day, 5000 RSV replicon cellsper well were plated in a 96-well plate. On the following day, compoundsto be tested were solubilized in 100% DMSO to 100×the desired finaltesting concentration. Cells were incubated with compounds for 7 days at37° C. in a 5% CO₂ atmosphere before measurement of the luciferasereadout. Cell viability (CC₅₀) was measured with a CellTiter-Glo cellproliferation assay (Promega). Compounds of Formula (I) showed activityin this RSV assay as indicated by the EC₅₀ values provided in Table 6.Compounds of Formula (I) also showed relatively low values of toxicityin the assay as indicated by the CC₅₀ values provided in Table 6.

Example D Ebola Antiviral Assay (EBOV)

HEp-2 cells were plated in 96-well plates at the density of 40,000cells/well. On the next day, modified vaccinia virus Ankara-T7 (MVA-T7)at the multiplicity of infection of 1 was added to provide T7 RNApolymerase. After 2 hours of viral transduction, each well wastransfected with Lipofectamine2000 (Thermo Fisher) with 0.01 g mixtureof 6 plasmids including Ebola minigenome, plasmids encoding Ebola L, NP,VP-35, VP-30 proteins. After 48 hours of further incubation, cells werelysed with RIPA buffer (Pierce), transferred to a black 96-well plateand the fluorescence was read at 0.1 sec/well at ex485 nm, emission 535nm on a Victor plate reader. Sigmoidal dose-response curves used togenerate 50% inhibitory or effective concentrations were analyzed bynonlinear regression using the four-parameter logistic equation(GraphPad Prism). Compounds of Formula (I) showed activity in this EBOVassay as indicated by the EC₅₀ values provided in Table 6. Compounds ofFormula (I) also showed relatively low values of toxicity in the assayas indicated by the CC₅₀ values provided in Table 6.

Example E Coronavirus Antiviral Assay

The human β-coronavirus strain OC43 was purchased from ATCC (Manassas,Va.; item numbers VR-1558 and VR-740, respectively). 24 hours prior todosing, HeLa human cervix epithelial cells (ATCC, CCL-2) or MRC-5 humanlung fibroblast (ATCC, CCL-171) were plated in 96 well plates at adensity of 1.5×10⁵/ml in DMEM medium supplemented with 10% fetal bovineserum, 1% HEPES buffer, 1% Penicillin/Streptomycin and 1% non-essentialamino acids (all Mediatech, Manassas, Va.). At the day of infection,serially diluted compounds were added to cells and incubated for 4hours. After the end of the 4 hour pre-incubation period, cells wereinfected with either coronavirus strain OC43 or 229E. The virus inoculumwas selected to cause 80-90% cytopathic effect. Infected cells wereincubated for five days at 37° C., 5% CO₂. To develop the assay, 100 μlmedia was replaced with 100 μl CellTiter-Glo® reagent (Promega, Madison,Wis.), and incubated for 10 min at room temperature. Luminescence wasmeasured on a Victor X3 multi-label plate reader. Potential compoundcytotoxicity was determined using uninfected parallel cultures.Compounds of Formula (I) showed activity in this assay against the humanβ-coronavirus strain OC43 as indicated by the EC₅₀ values provided inTable 6. Compounds of Formula (I) also showed relatively low values oftoxicity in the assay as indicated by the CC₅₀ values provided in Table6.

TABLE 6 EBOV HRV 1B OC43CoV DENV RSV EC50 CC50 EC50 CC50 EC50 CC50 EC50CC50 EC50 CC50 No. (uM) (uM) (uM) (uM) (uM) (uM) (uM) (uM) (uM) (uM) C10.8 51 0.12 6 0.065 69 0.13 22 0.02 3 5 25.3 >100 7.37 >100  2.74 >100 62.5 >100 4.1 >100 1.7 >100 0.25, 0.33 78, 69 0.02 43 7 0.2 14 0.15 12.40.056 13  0.0014 15, 21 0.03 21 8 0.5, 0.8 >100 1.3, 0.4 64 0.1 >500.11, 0.14 >100, 25  0.03, 0.026 30, 7.1 9  0.25 ~50 0.13 33 0.025 340.07 12 0.018 8.1 10 3.1 >100 2.3 >50 0.17 >100 11 >100 59 >50 >50 1.313.6 Compound No. “C1” is a comparison compound having the followingstructure:

Example F Dengue Polymerase Assay (DENVpol)

The enzyme activity of dengue virus NS5 polymerase domain (DENVpol,serotype 2, New Guinea C strain) was measured as an incorporation oftritiated NMP into acid-insoluble RNA products. DENVpol assay reactionscontained 100 nM recombinant enzyme, 50 nM heteropolymeric RNA, about0.5 μCi tritiated NTP, 0.33 μM of competing cold NTP, 40 mM HEPES (pH7.5), 3 mM dithiothreitol, and 2 mM MgCl₂. Standard reactions wereincubated for 3 hours at 30° C., in the presence of increasingconcentration of inhibitor. At the end of the reaction, RNA wasprecipitated with 10% TCA, and acid-insoluble RNA products were filteredon a size exclusion 96-well plate. After washing of the plate,scintillation liquid was added and radiolabeled RNA products weredetected according to standard procedures with a Trilux Topcountscintillation counter. The compound concentration at which theenzyme-catalyzed rate was reduced by 50% (IC₅₀) was calculated byfitting the data to a non-linear regression (sigmoidal). The IC₅₀ valueswere derived from the mean of several independent experiments and areshown in Table 7. Compounds of Formula (I) showed activity in thisassay.

Example G Rhinovirus Polymerase (HRV16pol) and HCV Polymerase (HCVpol)Assays

The enzyme activity of hepatitis C virus RNA polymerase (HCVpol) andhuman rhinovirus 16 RNA polymerase (HRV16pol) is measured as anincorporation of tritiated NMP into acid-insoluble RNA products. HCVpoland HRV16pol assay reactions contain 30-100 nM recombinant enzyme,50-500 nM heteropolymeric RNA, 0.5 μCi tritiated NTP, 0.1-1 μM of otherNTPs, in a standard reaction buffer containing MgCl₂. Enzymaticreactions are incubated for 2.5 hours at 30° C., in the presence ofincreasing concentration of inhibitor. At the end of the reaction, thetotal RNA is precipitated with 10% TCA, and acid-insoluble RNA productsare filtered on a size exclusion 96-well plate. After washing of theplate, scintillation liquid is added and radiolabeled RNA products aredetected according to standard procedures with a Trilux Microbetascintillation counter. The compound concentration at which theenzyme-catalyzed rate is reduced by 50% (IC₅₀) is calculated by fittingthe data to a non-linear regression (sigmoidal). Compounds of Formula(I) showed activity in these assays.

Example H RSV Polymerase Assay (RSVpol)

Standard RSV polymerase assays were conducted in the presence of 3 μLextract of RSV-infected cells in a reaction buffer containing 50 mMtris-acetate pH 8, 120 mM K-acetate, 4.5 mM MgCl₂, 5% glycerol, 2 mMEDTA, 50 μg/ml BSA, and 3 mM DTT. Varying concentration of NTPs wereused to initiate RNA synthesis for 120 minutes at 30 degrees, andradioactive 33P GTP (15 μCi) was used as tracer. The reaction wasstopped by adding 50 mM EDTA, and RNA samples were purified through G-50size exclusion spin columns and phenol-chloroform extraction. Theradio-labeled RNA products were resolved by electrophoresis on a 6%polyacrylamide TBE gel, and visualized and quantitated after beingexposed on a phosphorImager screen. Polymerase inhibition experiments(IC50s) were conducted the same way in the presence of increasingconcentration of NTP analogs. Compounds of Formula (I) showed activityin these assays.

Compound No. “C2” is a comparison compound having the followingstructure:

TABLE 7 HRV16pol HCVpol DENVpol RSVpol No. IC₅₀ (uM) IC₅₀ (uM) IC₅₀ (uM)IC₅₀ (uM) C2 0.27 1 3.6 0.12 12 0.13 0.4 1.1 0.03 13 0.21 >10 >10 >10 140.04 0.3 1.1 0.03

Although the foregoing has been described in some detail by way ofillustrations and examples for purposes of clarity and understanding, itwill be understood by those of skill in the art that numerous andvarious modifications can be made without departing from the spirit ofthe present disclosure. Therefore, it should be clearly understood thatthe forms disclosed herein are illustrative only and are not intended tolimit the scope of the present disclosure, but rather to also cover allmodification and alternatives coming with the true scope and spirit ofthe invention.

What is claimed is:
 1. A compound of Formula (I), or a pharmaceuticallyacceptable salt thereof, having the structure:

wherein: R^(1A) is selected from the group consisting of fluoro, cyano,azido, an unsubstituted C₂₋₄ alkenyl, an unsubstituted C₂₋₄ alkynyl, anunsubstituted C₁₋₄ alkoxy, an unsubstituted C₁₋₄ alkyl, and asubstituted C₁₋₄ alkyl, wherein said substituted C₁₋₄ alkyl issubstituted with one or more substituents selected from fluoro andchloro; R^(4A) is selected from the group consisting of fluoro, cyano,azido, an unsubstituted C₂₋₄ alkenyl, an unsubstituted C₂₋₄ alkynyl, anunsubstituted C₁₋₄ alkoxy, an unsubstituted C₁₋₄ alkyl, and asubstituted C₁₋₄ alkyl, wherein said substituted C₁₋₄ alkyl issubstituted with one or more substituents selected from fluoro andchloro; R^(2A), R^(3A), R^(a1), and R_(a2) are each independentlyhydrogen or deuterium; R^(5A) is selected from the group consisting ofhydrogen, an optionally substituted acyl, an optionally substitutedO-linked amino acid,

R^(6A), R^(7A) and R^(8A) are independently selected from the groupconsisting of absent, hydrogen, an optionally substituted C₁₋₂₄ alkyl,an optionally substituted C₃₋₂₄ alkenyl, an optionally substituted C₃₋₂₄alkynyl, an optionally substituted C₃₋₆ cycloalkyl, an optionallysubstituted C₃₋₆ cycloalkenyl, an optionally substituted aryl, anoptionally substituted heteroaryl, an optionally substituted aryl(C₁₋₆alkyl), an optionally substituted *—(CR^(15A)R^(16A))—O—C₁₋₂₄ alkyl, anoptionally substituted *—(CR^(17A)R^(18A))_(q)—O—C₁₋₂₄ alkenyl,

or R^(6A) is

and R^(7A) is absent or hydrogen; or R^(6A) and R^(7A) are takentogether to form a moiety selected from the group consisting of anoptionally substituted

and an optionally substituted

wherein the oxygens connected to R^(6A) and R^(7A), the phosphorus andthe moiety form a six-membered to ten-membered ring system; R^(9A) isindependently selected from the group consisting of an optionallysubstituted C₁₋₂₄ alkyl, an optionally substituted C₂₋₂₄ alkenyl, anoptionally substituted C₂₋₂₄ alkynyl, an optionally substituted C₃₋₆cycloalkyl, an optionally substituted C₃₋₆ cycloalkenyl,NR^(30A)R^(31A), an optionally substituted N-linked amino acid and anoptionally substituted N-linked amino acid ester derivative; R^(10A) andR^(11A) are independently an optionally substituted N-linked amino acidor an optionally substituted N-linked amino acid ester derivative;R^(12A), R^(13A) and R^(14A) are independently absent or hydrogen; eachR^(15A), each R^(16A), each R^(17A) and each R^(18A) are independentlyhydrogen, an optionally substituted C₁₋₂₄ alkyl or alkoxy; R^(19A),R^(20A), R^(22A) and R^(23A) are independently selected from the groupconsisting of hydrogen, an optionally substituted C₁₋₂₄ alkyl and anoptionally substituted aryl; R^(21A) and R^(24A) are independentlyselected from the group consisting of hydrogen, an optionallysubstituted C₁₋₂₄ alkyl, an optionally substituted aryl, an optionallysubstituted —O—C₁₋₂₄ alkyl, an optionally substituted —O-aryl anoptionally substituted —O-heteroaryl, an optionally substituted—O-monocyclic heterocyclyl and

R^(25A) and R^(29A) are independently selected from the group consistingof hydrogen, an optionally substituted C₁₋₂₄ alkyl and an optionallysubstituted aryl; R^(26A) and R^(27A) are independently —C═N or anoptionally substituted substituent selected from the group consisting ofC₂₋₈ organylcarbonyl, C₂₋₈ alkoxycarbonyl and C₂₋₈ organylaminocarbonyl;R^(28A) is selected from the group consisting of hydrogen, an optionallysubstituted C₁₋₂₄-alkyl, an optionally substituted C₂₋₂₄ alkenyl, anoptionally substituted C₂₋₂₄ alkynyl, an optionally substituted C₃₋₆cycloalkyl and an optionally substituted C₃₋₆ cycloalkenyl; R^(30A) andR^(31A) are independently selected from the group consisting ofhydrogen, an optionally substituted C₁₋₂₄-alkyl, an optionallysubstituted C₂₋₂₄ alkenyl, an optionally substituted C₂₋₂₄ alkynyl, anoptionally substituted C₃₋₆ cycloalkyl and an optionally substitutedC₃₋₆ cycloalkenyl; m and t are independently 0 or 1; p and q areindependently selected from the group consisting of 1, 2 and 3; r is 1or 2; s is 0, 1, 2 or 3; u is 1 or 2; and
 2. Z^(1A), Z^(2A), Z^(3A) andZ^(4A) are independently O or S The compound or pharmaceutically saltthereof of claim 1, wherein R^(1A) is cyano.
 3. The compound orpharmaceutically salt thereof of any one of claims 1 to 2, whereinR^(4A) is selected from the group consisting of fluoro, cyano, azido,and an unsubstituted C₁₋₄ alkyl.
 4. The compound or pharmaceuticallysalt thereof of claim 3, wherein R^(4A) is fluoro.
 5. The compound orpharmaceutically salt thereof of claim 3, wherein R^(4A) is cyano. 6.The compound or pharmaceutically salt thereof of claim 3, wherein R^(4A)is azido.
 7. The compound or pharmaceutically salt thereof of claim 3,wherein R^(4A) is an unsubstituted C₁₋₄ alkyl.
 8. The compound orpharmaceutically salt thereof of claim 3, wherein R^(4A) is asubstituted C₁₋₄ alkyl.
 9. The compound or pharmaceutically salt thereofof claim 8, wherein the substituted C₁₋₄ alkyl is selected from thegroup consisting of —(CH₂)₁₋₄Cl, —(CH₂)₁₋₄F and —CHF₂.
 10. The compoundor pharmaceutically salt thereof of claim 9, wherein the substitutedC₁₋₄ alkyl is selected from the group consisting of chloromethyl,fluoromethyl and difluoromethyl.
 11. The compound or pharmaceuticallysalt thereof of claim 10, wherein the substituted C₁₋₄ alkyl ischloromethyl.
 12. The compound or pharmaceutically salt thereof of claim10, wherein the substituted C₁₋₄ alkyl is fluoromethyl.
 13. The compoundor pharmaceutically salt thereof of any one of claims 1 to 12, whereinR^(5A) is hydrogen.
 14. The compound or pharmaceutically salt thereof ofany one of claims 1 to 12, wherein R^(5A) is


15. The compound or pharmaceutically salt thereof of claim 14, whereinR^(6A) and R^(7A) are hydrogen.
 16. The compound or pharmaceuticallysalt thereof of claim 14, wherein R^(6A) is


17. The compound or pharmaceutically salt thereof of claim 16, whereinR^(12A), R^(13A) and R^(14A) are hydrogen.
 18. The compound orpharmaceutically salt thereof of any one of claims 14 to 17, whereinZ^(1A) is O.
 19. The compound or pharmaceutically salt thereof of anyone of claims 1 to 12, wherein R^(5A) is


20. The compound of claim 19, wherein R^(8A) is an optionallysubstituted aryl; and R^(9A) is an optionally substituted N-linked aminoacid or an optionally substituted N-linked amino acid ester derivative.21. The compound or pharmaceutically salt thereof of claim 19 or 20,wherein Z^(2A) is O.
 22. The compound of claim 1, wherein the compoundof Formula (I) is selected from the group consisting of:

or a pharmaceutically acceptable salt of the foregoing.
 23. Apharmaceutical composition comprising an effective amount of a compoundof any one of claims 1 to 22, or a pharmaceutically acceptable saltthereof, and a pharmaceutically acceptable carrier, diluent, excipient,or combination thereof.
 24. A method of ameliorating or treating aPicornaviridae viral infection comprising administering an effectiveamount of a compound of any one of claims 1 to 22, or a pharmaceuticallyacceptable salt thereof, or the pharmaceutical composition of claim 23,to a subject suffering from the Picornaviridae viral infection.
 25. Themethod of claim 24, wherein the Picornaviridae viral infection is aRhinovirus infection.
 26. A method of ameliorating or treating aFlaviviridae viral infection comprising administering an effectiveamount of a compound of any one of claims 1 to 22, or a pharmaceuticallyacceptable salt thereof, or the pharmaceutical composition of claim 23,to a subject suffering from the Flaviviridae viral infection.
 27. Themethod of claim 26, wherein the Flaviviridae viral infection is a Denguevirus infection.
 28. The method of claim 26, wherein the Flaviviridaeviral infection is a Hepacivirus infection.
 29. A method of amelioratingor treating a Filoviridae viral infection comprising administering aneffective amount of a compound of any one of claims 1 to 22, or apharmaceutically acceptable salt thereof, or the pharmaceuticalcomposition of claim 23, to a subject suffering from the Filoviridaeviral infection.
 30. The method of claim 29, wherein the Filoviridaeviral infection is an Ebolavirus infection.
 31. A method of amelioratingor treating a Pneumoviridae viral infection comprising administering aneffective amount of a compound of any one of claims 1 to 22, or apharmaceutically acceptable salt thereof, or the pharmaceuticalcomposition of claim 23, to a subject suffering from the Pneumoviridaeviral infection.
 32. The method of claim 31, wherein the Pneumoviridaeviral infection is a human respiratory syncytial virus (HRSV) infection.33. A method of ameliorating or treating a Coronaviridae viral infectioncomprising administering an effective amount of a compound of any one ofclaims 1 to 22, or a pharmaceutically acceptable salt thereof, or thepharmaceutical composition of claim 23, to a subject suffering from theCoronaviridae viral infection.
 34. The method of claim 33, wherein theCoronaviridae viral infection is a human α-coronavirus viral infection.35. The method of claim 33, wherein the Coronaviridae viral infection isa human β-coronavirus viral infection.
 36. A panviral treatment, saidtreatment comprising an effective amount of the compound, or apharmaceutically acceptable salt thereof, of any one of claims 1 to 22.37. The panviral treatment of claim 36, wherein the compound, or apharmaceutically acceptable salt thereof, is effective to treat viralinfections caused by viruses in two or more families selected from thegroup consisting of Picornaviridae, Flaviviridae, Filoviridae,Pneumoviridae and Coronaviridae
 38. The panviral treatment of claim 36or claim 37, wherein the compound, or a pharmaceutically acceptable saltthereof, has low toxicity.
 39. The panviral treatment of any one ofclaims 36 to 38, wherein the viral infections are selected from aRhinovirus infection in the Picornaviridae family; a Dengue virusinfection or a Hepacivirus infection in the Flaviviridae family; anEbolavirus infection in the Filoviridae family; a human respiratorysyncytial virus (HRSV) infection in the Pneumoviridae family; and ahuman α-coronavirus viral infection or a human β-coronavirus viralinfection in the Coronaviridae family.
 40. The panviral treatment of anyone of claims 36 to 39, wherein the compound is selected from the groupconsisting of:

or a pharmaceutically acceptable salt of the foregoing.
 41. The panviraltreatment of any one of claims 36 to 40, wherein the treatment isformulated for administration to a subject having a Picornaviridae,Flaviviridae, Filoviridae, Pneumoviridae and/or Coronaviridae viralinfection.
 42. The panviral treatment of any one of claims 36 to 41,wherein the treatment is formulated in the form of a pharmaceuticalcomposition.
 43. Use of an effective amount of a compound of any one ofclaims 1 to 22, or a pharmaceutically acceptable salt thereof, in thepreparation of a medicament for ameliorating or treating aPicornaviridae viral infection.
 44. The use of claim 43, wherein thePicornaviridae viral infection is a Rhinovirus infection.
 45. Use of aneffective amount of a compound of any one of claims 1 to 22, or apharmaceutically acceptable salt thereof, in the preparation of amedicament for ameliorating or treating a Flaviviridae viral infection.46. The use of claim 45, wherein the Flaviviridae viral infection is aDengue virus infection.
 47. The use of claim 45, wherein theFlaviviridae viral infection is a Hepacivirus infection.
 48. Use of aneffective amount of a compound of any one of claims 1 to 22, or apharmaceutically acceptable salt thereof, in the preparation of amedicament for ameliorating or treating a Filoviridae viral infection.49. The use of claim 48, wherein the Filoviridae viral infection is anEbolavirus infection.
 50. Use of an effective amount of a compound ofany one of claims 1 to 22, or a pharmaceutically acceptable saltthereof, in the preparation of a medicament for ameliorating or treatinga Pneumoviridae viral infection.
 51. The use of claim 50, wherein thePneumoviridae viral infection is a human respiratory syncytial virus(HRSV) infection.
 52. Use of an effective amount of a compound of anyone of claims 1 to 22, or a pharmaceutically acceptable salt thereof, inthe preparation of a medicament for ameliorating or treating aCoronaviridae viral infection.
 53. The use of claim 52, wherein theCoronaviridae viral infection is a human α-coronavirus viral infection.54. The use of claim 52, wherein the Coronaviridae viral infection is ahuman β-coronavirus viral infection.
 55. A compound of Formula (Ia2), ora pharmaceutically acceptable salt thereof, having the structure:

wherein: R^(4A) is selected from the group consisting of: fluoro, cyano,azido and C₁₋₄alkyl substituted with one or more substituents selectedfrom fluoro and chloro; R^(5A) is hydrogen,

R^(9A) is

and R^(33A) is C₁₋₆ alkyl.